LED lamp emitting high luminous flux

ABSTRACT

where K is a constant, and range of the constant of K is 360˜450; range of value of a is 0.001˜0.01, range of value of b is 0.05˜0.3, and range of value of c is 5˜20.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 16/267,747 filed on Feb. 2, 2019, which claims priority to thefollowing Chinese Patent Applications No. CN 201810130085.3 filed onFeb. 8, 2018, CN 201810479044.5 filed on May 18, 2018, CN 201810523952.Xfiled on May 28, 2018, CN 201810573322.3 filed on Jun. 6, 2018, CN201810634571.9 filed on Jun. 20, 2018, CN 201810763800.7 field on Jul.12, 2018, CN 201810763089.5 filed on Jul. 12, 2018, CN 201810972904.9filed on Aug. 24, 2018, CN 201811172470.0 filed on Oct. 9, 2018, CN201811295618.X filed on Nov. 11, 2018, CN 201811299410.5 filed on Nov.2, 2018, CN 201811347198.5 filed on Nov. 13, 2018, CN 201811378174.6filed on Nov. 19, 2018, and CN 201811466198.7 filed on Dec. 3, 2018, thedisclosures of which are incorporated herein in their entirety byreference.

FIELD OF THE INVENTION

The invention relates to lighting, particularly to LED lamps emittinghigh luminous flux.

BACKGROUND OF THE INVENTION

Because LED lamps possess advantages of energy saving, high efficiency,environmental protection and long life, they have been widely adopted inthe lighting field. For LED lamps used as an energy-saving green lightsource, a problem of heat dissipation of high-power LED lamps becomesmore and more important. Overheating will result in attenuation oflighting efficiency. If waste heat from working high-power LED lampscannot be effectively dissipated, then the life of LED lamps will bedirectly negatively affected. As a result, in recent years, solution ofthe problem of heat dissipation of high-power LED lamps is an importantissue for the industry.

OBJECT AND SUMMARY OF THE INVENTION

The LED lamp described in the present disclosure includes an LED (lightemitting diode) lamp including a lamp shell including a lamp head, alamp neck and a sleeve, the lamp head connects to the lamp neck whichconnects to the sleeve; a passive heat dissipating element having a heatsink connected to the lamp shell, wherein the heat sink comprises finsand a base, the sleeve of the lamp shell is located in the heat sink,the lamp neck projects from the heat sink, height of the lamp neck is atleast 80% of height of the heat sink; a power source having a firstportion and a second portion, wherein the first portion of the powersource is disposed in both the lamp neck and the lamp head of the lampshell, and the second portion of the power source is disposed in theheat sink of the passive heat dissipating element; a light emittingsurface connected to the heat sink of the passive heat dissipatingelement and comprising LED chips electrically connected to the powersource, wherein the light emitting surface and the heat sink areconnected to form a heat transferring path from the LED chips to thepassive heat dissipating element; a first heat dissipating channelformed in a first chamber of the lamp shell for dissipating heatgenerated from the power source while the LED lamp is working, and thefirst chamber is located between bottom of the LED lamp and an upperportion of the lamp neck; and a second heat dissipating channel formedin the heat sink and between the fins and the base of the heat sink fordissipating the heat generated from the LED chips and transferred to theheat sink; wherein the first heat dissipating channel comprises a firstend on the light emitting surface to allow air flowing from outside ofthe LED lamp into the first chamber, and a second end on the upperportion of the lamp neck of the lamp shell to allow air flowing frominside of the first chamber out to the LED lamp; wherein the second heatdissipating channel comprises a third end on the light emitting surfaceto allow air flowing from outside of the LED lamp into the second heatdissipating channel, and flowing out from spaces between every adjacenttwo of the fins; wherein a third aperture is located in a central regionof the light emitting surface, and the third aperture forms an airintake of both the first heat dissipating channel and the second heatdissipating channel; wherein a lateral outline of the LED lamp detoursaround an axis of the LED lamp 360 degrees to turn around to form ancontour of the LED lamp, any point on the outline meets a formula asfollows: y=−ax3+bx2−cx+K; where K is a constant, and range of theconstant of K is 360-450; range of value of a is 0.001˜0.01, range ofvalue of b is 0.05˜0.3, and range of value of c is 5˜20; wherein overallweight of the LED lamp is less than 1.7 kg, when the LED lamp isprovided with power of 200 W, the LED chips are lit up and emit luminousflux of at least 25000 lumens.

Preferably, the values of a, b and c are to meet a relation of follows:y=−0.0012×3+0.2235×2−14.608×+K.

Preferably, the heat sink includes a lower portion and an upper portion,the lower portion of the heat sink has large width and heat dissipatingarea than the upper portion.

Preferably, cross-sectional area of the lamp neck axially upward tapersoff.

Preferably, the outline of the LED lamp is a substantially S-shapedcurve including a curve on the lamp neck and a curve on the heat sink.

Preferably, further comprising a lamp cover with a light output surfaceand an end surface, wherein the end surface is formed with a vent to letair flowing from outside of the LED lamp into both the first channel andthe second channel through the vent.

Preferably, the first end is projected onto the end surface in the axisof the LED lamp to occupy an area on the end surface, which is definedas a first portion, another area on the end surface is defined as asecond portion, and the vent in the first portion is greater than thevent in the second portion in area.

Preferably, the heat sink comprises first fins and second fins, bottomsof both the first fins and the second fins in the axis of the LED lampconnect to the base, the first fins interlace with the second fins atregular intervals, and one of the second fins includes a third portionand two fourth portions, the two fourth portions are symmetrical aboutthe third portion.

Preferably, each of the first fins is divided into two portions in aradial direction of the LED lamp, the two portions are divided with agap portion, the third portion is connected to the fourth portionthrough a transition portion, the transition portion has a buffersection and a guide section, a direction of any tangent of the guidesection is separate from the gap portion.

Preferably, the second end on the upper portion of the lamp neck of thelamp shell is formed with a venting hole, the lamp shell has an airflowlimiting surface which extends radially outwardly and is located awayfrom the venting hole, the airflow limiting surface cloaks at least partof the fins.

Preferably, upper portions of at least part of the fins in the axialdirection of the LED lamp correspond to the airflow limiting surface.

Preferably, the sleeve has an upper portion and a lower portion, theupper portion is connected to the lower portion through an air guidingsurface, a diameter of cross-section of the air guiding surface downwardtapers off along the axis of the LED lamp.

Preferably, the sleeve includes a first portion and a second portion inthe axial direction, the second portion is a part of the sleeve belowthe air guiding surface, electronic components of the power source,which are located in the second portion of the sleeve, includeelectrolytic capacitors.

Preferably, the power source includes a heat-generating element, theheat-generating element is in contact with the lamp head through athermal conductor and the heat-generating element is fastened to thelamp head through the thermal conductor.

Preferably, the lamp head includes a metal portion, at least part of aninner side of the metal portion constitutes a wall of the inner chamberof the lamp shell to make the thermal conductor directly connecting withthe metal portion and performing heat dissipation by the metal portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed descriptions, given by way of example, and notintended to limit the present invention solely thereto, will be best beunderstood in conjunction with the accompanying figures:

FIG. 1 is a structural schematic view of one embodiment of an LED lampaccording to aspects of the invention;

FIG. 2 is a schematic cross-sectional view of the LED lamp of FIG. 1;

FIG. 3 is an exploded view of the LED lamp of FIG. 1;

FIG. 4 is a schematic cross-sectional view of the LED lamp of FIG. 1,which shows the first heat dissipating channel and the second heatdissipating channel;

FIG. 5 is a perspective view of the LED lamp of FIG. 1;

FIG. 6 is a structural schematic view of FIG. 5 without the light outputsurface;

FIG. 7 is an exploded view of another embodiment of an LED lampaccording to aspects of the invention, which shows a shading ring;

FIG. 8 is a perspective view of another embodiment of an LED lampaccording to aspects of the invention;

FIG. 9 is a schematic view of FIG. 8 without the light output surface;

FIG. 10 is a cross-sectional view of another embodiment of the LED lampaccording to aspects of the invention, which shows the flat light outputsurface;

FIG. 11 is a schematic view of an end surface of the lamp cover of anembodiment;

FIGS. 12A-12G are schematic views of some embodiments of the lamp cover;

FIG. 13 is a cross-sectional view of an LED lamp without a lamp cover,according to another embodiment of the present invention;

FIG. 14 is a perspective view of an LED lamp, according to anotherembodiment of the present invention;

FIG. 15 is a cross-sectional view of the LED lamp of FIG. 14;

FIG. 16 is a top view of the heat sink of the LED lamp of FIG. 14;

FIG. 17 is an enlarged view of portion E in FIG. 16;

FIG. 18 is a schematic view showing a vortex formed by air near thesecond fins according to another embodiment of the present invention;

FIG. 19 is a partially schematic view of the heat sink of anotherembodiment;

FIG. 20 is a bottom view of the LED lamp of FIG. 1 without the lampcover;

FIG. 21 is an enlarged view of portion A in FIG. 20;

FIG. 22 is a cross-sectional view of an LED lamp, according to anotherembodiment of the present invention;

FIG. 23 is an enlarged view of the LED lamp of portion C in FIG. 22;

FIG. 24 is a perspective view of a lamp cover, according to anotherembodiment of the present invention;

FIG. 25 is a schematic view of the combination of the fins and the LEDchips of an embodiment;

FIG. 26 is a schematic view of the combination of the fins and the LEDchips, according to some embodiments of the present invention;

FIG. 27 is a schematic view of another embodiment of the light board;

FIGS. 28A-28C are perspective views of the power source, according tosome embodiments of the present invention;

FIG. 28D is a main view of the power source of the embodiment of FIGS.28A-280;

FIG. 29 is a schematic view of the power source, according to oneembodiment of the present invention;

FIG. 30 is a main view of the counterweight of FIG. 29;

FIG. 31 is a side view of the counterweight of FIG. 30;

FIG. 32 is a schematic view of a transformer, according to oneembodiment of the present invention;

FIG. 33 is a schematic of the power source, according to an embodimentof the present invention;

FIG. 34 is an enlarged view of portion B in FIG. 2;

FIG. 35 is a partially schematic view of an LED lamp;

FIG. 36 is a cross-sectional view of the LED lamp of another embodiment;

FIG. 37 is a schematic view of an arrangement of the convection channelsof the LED lamp of FIG. 36;

FIG. 38 is a main view of the LED lamp, according to one embodiment ofthe present invention;

FIG. 39 is a schematic view of the combination of the LED lamp with alampshade, according to one embodiment of the present invention;

FIG. 40 is a main view of the LED lamp, according to one embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

To make the present invention understandable and readable, the followingdisclosure will now be described in the following embodiments withreference to the drawings. The following descriptions of variousembodiments of this invention are presented herein for purpose ofillustration and giving examples only. It is not intended to beexhaustive or to be limited to the precise form disclosed. These exampleembodiments are just examples and many implementations and variationsare possible without the details provided herein. Some terms mentionedin the following description, such as “in an axis”, “above” or “under”,are used for clear structural relationship of elements, but not a limitto the present invention. In the present invention, the terms“perpendicular”, “horizontal” and “parallel” are defined in a range of±10% based on a standard definition. For example, “perpendicular”(perpendicularity) means the relationship between two lines which meetat a right angle (90 degrees). However, in the present invention,“perpendicular” may encompass a range from 80 degrees to 100 degrees. Inaddition, “using condition” or “using status” mentioned in the presentdisclosure means a “head-up” hanging scenario. Exceptions will beparticularly described.

FIG. 1 is a structural schematic view of an embodiment of an LED lampaccording to certain aspects of the invention. FIG. 2 is a schematiccross-sectional view of the LED lamp of FIG. 1. FIG. 3 is an explodedview of the LED lamp of FIG. 1. As shown in the figures, the LED lampincludes a heat sink 1, a lamp shell 2, a light board 3, a lamp cover 4and a power source 5. In this embodiment, the light board 3 is connectedto the heat sink 1 by attachment for rapidly transferring heat from thelight board 3 to the heat sink 1 when the LED lamp is working. In someembodiments, the light board 3 is riveted to the heat sink 1. In someembodiments, the light board3 is screwed to the heat sink 1. In someembodiments, the light board 3 is welded to the heat sink 1. In someembodiments, the light board 3 is adhered to the heat sink 1. In thisembodiment, the lamp shell 2 is connected to the heat sink 1, the lampcover 4 covers the light board 3 to make light emitted from the lightboard 3 pass through the lamp cover to project out. The power source 5is located in a chamber of the lamp shell 2 and the power source 5 is ECto the LED chips 311 for providing electricity.

FIG. 4 is a schematic cross-sectional view of the LED lamp. As shown inFIGS. 2 and 4, the chamber of the lamp shell 2 of this embodiment isformed with a first heat dissipating channel 7 a. An end of the firstheat dissipating channel is formed with a first air inlet 2201. Anopposite end of the lamp shell 2 is formed with a venting hole 222 (atan upper portion of the lamp neck 22). Air flows into the first heatdissipating channel 2201 and flows out from the venting hole 222 forbringing out heat in the first heat dissipating channel 7 a (primarily,heat of the working power source 5). As for the path of heatdissipation, heat generated from the heat-generating components of theworking power source 5 is transferred to air (around the heat-generatingcomponents) in the first heat dissipating channel 7 a by thermalradiation first, and then external air enters the first heat dissipatingchannel 7 a by convection to bring out internal air to make heatdissipation. In this embodiment, the venting hole 222 at the lamp neck22 can also make direct heat dissipation.

As shown in FIGS. 1, 2 and 4, a second heat dissipating channel 7 b isformed in the fins and the base 13 of the heat sink 1. The second heatdissipating channel 7 b has a second air inlet 1301. In this embodiment,the first air inlet 2201 and the second air inlet 1301 share the sameopening formed on the light board 3. This will be described in moredetail later. Air flows from outside of the LED lamp into the second airinlet 1301, passes through the second heat dissipating channel 7 b andfinally flows out from spaces between the fins 11 so as to bring outheat of the fins 11 to enhance heat dissipation of the fins 11. As forthe path of heat dissipation, heat generated from the LED chips isconducted to the heat sink 1, the fins 11 of the heat sink 1 radiate theheat to surrounding air, and convection is performed in the second heatdissipating channel 7 b to bring out heated air in the heat sink 1 tomake heat dissipation.

As shown in FIGS. 1 and 4, the heat sink 1 is provided with a third heatdissipating channel 7 c formed between adjacent two of the fins 11 or ina space between two sheets extending from a single fin 11. A radialouter portion between two fins 11 forms an intake of the third heatdissipating channel 7 c. Air flows into the third heat dissipatingchannel 7 c through the radial outer portion of the LED lamp to bringout heat radiated from the heat sink 11 to air.

FIG. 5 is a perspective view of the LED lamp of an embodiment, whichshows assembling of the heat sink 1 and the lamp cover 4. FIG. 6 is astructural schematic view of FIG. 5 without the light output surface 43.As shown in FIGS. 5 and 6, in this embodiment, the lamp cover 4 includesa light output surface 43 and an end surface 44 with a vent 41. Airflows into both the first heat dissipating channel 7 a and the secondheat dissipating channel 7 b through the vent 41. When the LED chips 311(shown in FIG. 6) are illuminated, the light passes through the lightoutput surface 43 to be projected from the lamp cover 4. In thisembodiment, the light output surface 43 may use currently availablelight-permeable material such as glass, PC, etc. The term “LED chip”mentioned in all embodiments of the invention means all light sourceswith one or more LEDs (light emitting diodes) as a main part, andincludes but is not limited to an LED bead, an LED strip or an LEDfilament. Thus, the LED chip mentioned herein may be equivalent to anLED bead, an LED strip or an LED filament.

In this embodiment, area of the light output surface 43 (area of asingle side of the light output surface 43, i.e. area of surface of theside away from the LED chips 311) is above three times as large as areaof light emitting surface of all the LED chips 31 but does not exceedten times. Width of the light output region can be controlled when it isprovided sufficiently.

As shown in FIGS. 5 and 6, in this embodiment, an inner reflectingsurface 4301 is disposed inside the light output surface 43 of the lampcover 4. The inner reflecting surface 4301 is disposed in the innercircle of the array of LED chips 311. In an embodiment, an outerreflecting surface 4302 is disposed in the outer circle of the array ofLED chips 311. The outer reflecting surface 4302 corresponds to the LEDchips 311 on the light board 3. The arrangement of both the innerreflecting surface 4301 and the outer reflecting surface 4302 is usedfor adjusting a light emitting range of the LED chip set 31 to make thelight concentrated and to increase brightness in a local area. Forexample, under the condition of the same luminous flux, illuminance ofthe LED lamp can be increased. In one example, all the LED chips 311 inthis embodiment are mounted on the bottom side of the light board 3 (ina using status). In this embodiment, the LED lamp of the presentembodiment does not emit lateral light from the LED chips 311. Whenworking, the primary light emitting surfaces of the LED chips 311 arecompletely downward. At least 60% of the light from the LED chips 311are emitted through the light output surface 43 without reflection. As aresult, in comparison with those LED lamps with lateral light (thelateral light is reflected by a cover or a lampshade to be emitteddownward, and in theory there must be part of light loss in the processof reflection.) The LED chips 311 in this embodiment possess betterlight emitting efficiency. In one example, under the condition of thesame lumen value (luminous flux), the LED lamp in the present embodimentpossesses higher illuminance. And the emitted light can be concentratedto increase illuminance in a local area by the arrangement of both theinner reflecting surface 4301 and the outer reflecting surface 4302, forexample, in an area under the LED lamp between 120 degrees and 130degrees (a light emitting range under the LED lamp between 120 degreesand 130 degrees). When the LED lamp is installed at a relatively highposition, in the same angular range of light emitting, the lit area ofthe LED lamp still satisfies the requirement and illuminance in thisarea can be higher. The inner reflecting surface 4301 is used forreflecting part of light emitted from the innermost LED chips 311 of theLED chip set 31. The outer reflecting surface 4302 is used forreflecting part of light emitted from the outermost LED chips of the LEDchipset 31. The outermost LED chips 311 are greater than the innermostLED chips 311 in number. The outer reflecting surface 4302 is greaterthan the inner reflecting surface 4301 in area. Because the outermostportion of the LED chip set 31 includes more LED chips than theinnermost portion, larger reflecting area is beneficial to regulatelight output.

In this embodiment, the inner reflecting surface 4301 and the outerreflecting surface 4302 have first area A1 and second area A2,respectively. The LED chips 311 in the outermost portion of the LED chipset 31 and in the innermost portion of the LED chip set 31 are N1 and N2in number, respectively. Their relationship is:(A1/N1):(A2/N2)=0.4˜1

When the ratio of area of the inner reflecting surface 4301corresponding to a single LED chip 311 in the innermost portion of theLED chip set 31 to area of the outer reflecting surface 4302corresponding to a single LED chip 311 in the outermost portion of theLED chip set 31 falls in the above range, both the LED chips 311 in theinnermost portion of the LED chip set 31 and the LED chips 311 in theoutermost portion of the LED chip set 31 have a better effect of lightoutput.

As shown in FIG. 6, an inner edge of the inner reflecting surface 4301abuts against the light board 3 to prevent light from passing throughgaps between the inner reflecting surface 4301 and the light board 3 toavoid loss of part of light. Identically, an inner edge of the outerreflecting surface 4302 abuts against the light board 3 to prevent lightfrom passing through gaps between the outer reflecting surface 4302 andthe light board 3 to avoid loss of part of light.

As shown in FIG. 2, in this embodiment, an angle a is formed between twoextending lines of both the inner and outer reflecting surfaces 4301,4302. The angle a is between 80 degrees and 150 degrees. Preferably, theangle a is between 90 degrees and 135 degrees. More preferably, theangle a is between 100 degrees and 120 degrees. A reflecting-cup-likestructure is formed between the inner and outer reflecting surfaces4301, 4302 so as to control a light output range of the LED chips 311 orincrease local intensity. In this embodiment, an angle between the outerreflecting surface 4302 and the light board 2 is 30 to 60 degrees. Insome embodiments, the angle is 40 to 50 degrees.

As shown in FIG. 2, in this embodiment, the inner reflecting surface4301 is lower than the outer reflecting surface 4302 in height. Theheight means a height of each of the both in an axis of the LED lamp. Bythe configuration of the inner reflecting surface 4301 being lower thanthe outer reflecting surface 4302 in height, decrease of a lightdistribution under the LED lamp can be avoided and a central portion ofthe light distribution region of the LED lamp can be prevented to be adark part. In this embodiment, height of the outer reflecting surface4302 in the axis of the LED lamp is not greater than 20 mm. Preferably,height of the outer reflecting surface 4302 in the axis of the LED lampis not greater than 15 mm. On the other hand, to control overall heightof the LED lamp, height of the outer reflecting surface 4302 accountsfor not over 9% of overall height of the LED lamp. Preferably, height ofthe outer reflecting surface 4302 accounts for not over 6% of overallheight of the LED lamp. As for functions of the outer reflecting surface4302, in some embodiments, height of the outer reflecting surface 4302has to account for above 2% of overall height of the LED lamp.Preferably, in some embodiments, height of the outer reflecting surface4302 accounts for above 3% of overall height of the LED lamp. In oneexample, comprehensively considering control of height of the LED lampand functions of reflection, light concentration, anti-glare, etc., itis necessary that height of the outer reflecting surface 4302 accountsfor 2%-9% of overall height of the LED lamp. Preferably, height of theouter reflecting surface 4302 accounts for 3%-6% of overall height ofthe LED lamp.

In the LED lamps in some embodiments, both the inner and outerreflecting surfaces can be omitted, for example, a shading ring 47 maybe disposed. As shown in FIG. 7, the shading ring 47 is disposed on aperiphery of the lamp cover 4 to improve efficiency of light output ofthe lamp. A surface of the shading ring 47 possesses a reflecting effect(similar to the outer reflecting surface 4302 as mentioned in theprevious embodiment). When the lamp cover 4 is attached on the heat sink1, the shading ring 47 nears a periphery of the light board 3, forexample, an outer diameter of the shading ring 47 is the same as orslightly greater than that of the light board 3.

As show in FIGS. 5 and 6, in this embodiment, in order to prevent dustfrom covering on the LED chips 311 to reduce light efficiency of the LEDchips or affect heat dissipation of the LED chips 311, the LED chips 311may be received in a sealed room. For example, a sealed chamber 9 isformed between the light output surface 43, the inner reflecting surface4301, the outer reflecting surface 4302 and the light board 3 (this term“sealed” mentioned here may mean “without obvious pores”, not includingunavoidable gaps in an assembling process). In some embodiments, whenomitting both the inner and outer reflecting surfaces 4301, 4302, thesealed chamber 9 is formed between the light output surface 43 and thelight board 3 or between the light output surface 43, the heat sink 1and the light board 3.

FIG. 8 is a perspective view of another embodiment of the LED lamp ofthe invention. It differs from the above embodiment by holes formed inthe chamber 9. FIG. 9 is a schematic view of FIG. 8 without the lightoutput surface 43. As shown in FIGS. 8 and 9, in some embodiments, achamber 9 is formed between the light cover 4 and the light board 3. Indetail, the chamber 9 is formed between the light output surface 43, theinner reflecting surface 4301, the outer reflecting surface 4302 and thelight board 3 and the LED chips of the light board 3 are located in thechamber 9. The chamber 9 has first apertures 91 and second apertures 92.The first apertures 91 are configured to communicate with the outside,and the second apertures 92 are configured to communicate simultaneouslywith both the first heat dissipating channel 7 a and the second heatdissipating channel 7 b. In an aspect of heat dissipation, airconvection is formed in the chamber 9 to bring out part of heatgenerated from the LED chips 311, and outside air flows into the LEDlamp through the chamber 9 so as to enhance convection in both the firstheat dissipating channel 7 a and the second heat dissipating channel 7b. In some embodiments, both the inner and outer reflecting surfaces4301, 4302 may be omitted. In one example, a chamber 9 is formed betweenthe light output surface 43 and the light board 3.

As shown in FIG. 8, in some embodiments, the light output surface 43 isprovided with a hole to form the first apertures 91. Preferably, thefirst apertures 91 are annularly located at a circumferential portion ofthe light output surface 43 to make it not affect the effect of lightpenetration of the light output surface 43. In an aspect of structure,the light output surface 43 may be thermally deformed while the LED lampis working. The first apertures 91 makes the light output surface 43have a deformable space to prevent the light output surface 43 frombeing deformed to press the heat sink and cause damage of the lightoutput surface 43. In this embodiment, the first apertures 91 areannularly located at a circumferential portion of the light outputsurface 43. As a result, air convection can be enhanced and structuralstrength of the light output surface 43 heated can also be reinforced.

As shown in FIG. 9, in some embodiments, the inner reflecting surface4301 is provided with notches to form the second apertures 92. In thisembodiment, the second apertures 92 are annularly located at acircumferential portion of the inner reflecting surface 4301. The ratioof the number of the second apertures 92 to that of the first apertures91 is about 1:1˜2, preferably, 1:1.5. Thus, air intake and outtake canbe balanced. In other embodiments, both the first apertures 91 and thesecond apertures 92 may also be formed at other portions of the lampcover 4 such as the light board 3 or the base 13 of the heat sink 1.

As shown in FIGS. 8 and 9, in some embodiments, a chamber 9 is formedbetween the light cover 4 and the light board 3. In detail, the chamber9 is formed between the light output surface 43, the inner reflectingsurface 4301, the outer reflecting surface 4302 and the light board 3and the LED chips 311 of the light board 3 are located in the chamber 9.The chamber 9 has pressure release apertures to prevent temperature andpressure in the chamber from being raised by the working LED chips 311.The pressure release aperture may be the first apertures 91 of the lightoutput surface 43, the second apertures 92 of the inner reflectingsurface 4301, or holes at the heat sink 1 or the light board 3, whichcommunicate with the chamber 9.

As shown in FIG. 4, the distance between the light output surface 43 andthe light board 3 is gradually outwardly larger and larger so as to makethe light output surface 43 concave. Thus, in comparison with a flatsurface, such a light output surface 43 can be structurally reinforced.In addition, the gradually smooth slant of the light output surface 43does not has an angle so as to make thickness of the light outputsurface 43 even not to affect an effect of light output. Finally, in anaspect of use, the light board 3 generates heat from the light sourcewhile the LED lamp is working. If the light output surface 43 is a flatplane parallel to the horizon (the LED lamp is hung on a ceiling), thenthe heated light output surface 43 will horizontally thermally expand.As a result, the heat sink 1 may be damaged by being pressed. In thisembodiment, when the light output surface 43 is of a concave shape, itsexpansion direction will be different from the above, for example, theexpansion direction is divided into a horizontal portion and a downwardvertical portion. This can reduce the thermal expansion in thehorizontal direction to prevent the lamp cover 4 from being damaged bybeing pressed by the heat sink 1.

As shown in FIG. 10, in some embodiments, the light output surface 43may also be a flat plane, but a thermal expansion coefficient of thematerial of the light output surface 43, a distance between the lightoutput surface 43 and the heat sink 1 and resistance to deformation ofthe light output surface 43 should be seriously considered. For example,when the light output surface 43 is a flat plane, the distance betweenthe light output surface 43 and the heat sink 1 should be large enoughto guarantee expansion of the light output surface 43 not to be pressedby the heat sink 1.

As shown in FIG. 11, a diameter of a maximum inscribed circle of thevent 41 is less than 2 mm, preferably, 1.0˜1.9. mm. As a result, bothbugs and most dust can be resisted, and venting efficiency of the vent41 can be kept great enough. In one example, alternatively, the vent 41defines both a length direction and a width direction, i.e. the vent hasa length and a width, and the length is greater than the width. Thelargest width of inscribed circle of the vent 41 may be less than 2 mm.In an embodiment, the largest width is from 1 mm to 1.9 mm. In addition,the largest width of the vent 41 may be greater than 1 mm.

If the width of the vent 41 is less than 1 mm, then more pressure isrequired to push air to enter the vent 41, which is advanced forventing.

FIGS. 12A-12G show shapes of some embodiments of the vent 41. As shownin FIGS. 12A-12G, the vent 41 may be circular, strip-shaped, arced,trapezoidal, diamond or their combination. As shown in FIG. 12A, whenthe vent 41 is configured to be circular, its diameter should be lessthan 2 mm to resist bugs and most dust and venting efficiency of thevent 41 can be kept great enough. As shown in FIGS. 12B and 12C, whenthe vent 41 is configured to be strip-shaped or arced, its width shouldbe less than 2 mm to accomplish the above effects. As shown in FIG. 12D,when the vent 41 is configured to be trapezoidal, its lower base shouldbe less than 2 mm to accomplish the above effects. As shown in FIG. 12E,when the vent 41 is configured to be round-cornered rectangular, itswidth should be less than 2 mm to accomplish the above effects. As shownin FIGS. 12F and 12G, when the vent 41 is configured to be triangular ordrop-shaped, a diameter of its maximum inscribed circle should be lessthan 2 mm.

In some embodiments, the vent 41 on the end surface 44 is multiple innumber. For example, the vents 41 may be annularly arranged on the endsurface 44 for even air intake. The vents 41 may also be radiallyarranged on the end surface 44. The vents 41 may also be irregularlyarranged.

In FIG. 12A, there are two broken lines on the end surface 44. The innerbroken line represents a position the first air inlet 2201 (as shown inFIG. 2) is projected onto the end surface 44. The region within theinner broken line is defined as a first portion (first opening region433). The region between the inner circle and the outer circle isdefined as a second portion (second opening region 434). In thisembodiment, the first air inlet 2201 is projected onto the end surfacein an axis of the LED lamp to occupy an area on the end surface 44, itis the first portion (first opening region 433). The other area on theend surface 44 is the second portion (second opening region 434). Thevent 41 in the first portion is greater than the vent 41 in the secondportion in area. Such an arrangement is advantageous to making most airflow into the first heat dissipating channel 7 a for better effect ofheat dissipation to the power source 5 and reduction of rapidly aging ofelectronic components of the power source 5. These features are alsoavailable to the vent 41 in other embodiments.

In other embodiments, the first air inlet 2201 is projected onto the endsurface 44 in an axis of the LED lamp to occupy an area on the endsurface 44, which may be a first portion (first opening region 433). Theother area on the end surface 44 may be a second portion (second openingregion 434). The vent 41 in the first portion is smaller than the vent41 in the second portion in area. As a result, heat of the fins 11 canbe better dissipated to perform better heat dissipation to the LED chips311 and prevent a region around the LED chips 311 from forming hightemperature. In detail, area of both the first portion and the secondportion can be selected according to actual requirements.

In some applications, there may be a limit of overall weight of an LEDlamp. For example, when an LED lamp adopts an E39 head, its maximumweight limit is 1.7 Kg. Thus, besides the fundamental elements such as apower source, a lamp cover and a lamp shell, in some embodiments, weightof a heat sink is limited within 1.2 Kg. For some high-power LED lamps,the power is about 150 W-300 W, and their luminous flux can reach 20000lumens to 45000 lumens. Under a limit of weight, a heat sink shoulddissipate heat from an LED lamp with 20000-45000 lumens. Under acondition of heat dissipation of natural convection, usually power of 1W needs area of heat dissipation of at least 35 square cm. The followingembodiments intend to reduce area of heat dissipation for power of 1 Wunder guarantee of a receiving space of the power source 5 and effect ofheat dissipation. Under a precondition of weight limit of the heat sink1 and limit of the power source 5, the best effect of heat dissipationcan be accomplished.

As shown in FIGS. 1 and 2, in this embodiment, the LED lamp includespassive heat dissipating elements which adopt natural convection andradiation as a heat dissipating manner without any active heatdissipating elements such as a fan. The passive heat dissipating elementin this embodiment includes a heat sink 1 composed of fins 11 and a base13. The fins 11 radially extend from and connect to the base 13. Whenusing the LED lamp, at least part of heat from the LED chips 311 isconducted to the heat sink 1 by thermal conduction. At least part ofheat occurring from the heat sink 1 is transferred to external air bythermal convection and radiation. A diameter of a radial outline of theheat sink 1, in a hanging status as shown in the figures, tapers offupward or is substantially in a taper shape for a better match with alampshade. When the heat sink 1 in this embodiment is dissipating heat,at least part of heat is thermally radiated to air therearound toperform heat dissipation.

As shown in FIGS. 2,4 and 5, the base 13 of the heat sink 1 has a lowerend 133 located under the base 13, i.e. both the lower end 133 and thelight board 3 are located on the same side. In this embodiment, thelower end 133 protrudes from the light board 3 in an axis of the LEDlamp. In a using (hanging) status of the light board 3 being downward,the lower end 133 is lower than the light board 3 in position. As aresult, the position of the lower end 133 can protect the LED board 3.When collision occurs, the lower end 133 will collide first to preventthe light board 3 from colliding. As shown in FIGS. 2 and 4, in anotheraspect, the base 13 has a recess 132 in which the light board 3 isplaced. The recess 132 is of a cylindrical shape or a substantiallycylindrical shape, or a cylindrical platform structure. When the recess132 is of a cylindrical shape, a diameter of the cylinder is less thanthat of the base 13. The recess 132 in the base 13 is advantageous toreducing a glare effect of the LED lamp and improve direct vision andcomfort of users (inner walls of the recess 132 screen at least part oflateral light from the LED chips 311 to decrease glare). In someembodiments, the base 13 may have no recess. In some embodiments, tomake both the light board 3 and the heat sink 1 have maximum contactarea to guarantee a heat dissipation effect, a surface of the base 13 isa flat plane.

FIG. 13 is a cross-sectional view of an LED lamp of an embodimentwithout the lamp cover 4. As shown, in some embodiments, the lower end133 is configured to be slanted (relative to the horizon when the LEDlamp is being hung). When the slant is flat and straight in a radialdirection, an angle between the slant and the horizon is 3˜4 degrees. Inother embodiments, the angle is greater than 0 degrees but less than 6degrees. In some embodiments, when the slant is arced in a radialdirection, an angle between a tangent plane of the arced surface and thehorizon is 3˜4 degrees. In other embodiments, the angle is greater than0 degrees but less than 6 degrees. When the lower end 133 is inclined toa specific angle (e.g. an angle between the lower end 133 and the outerreflecting surface 4302 is 120˜80 degrees), it could serve as anextension of the outer reflecting surface 4302 to perform reflection.

FIG. 14 is a perspective view of an LED lamp of an embodiment of thepresent invention. As shown in FIGS. 2 and 14, another side of the base13 of the heat sink 1, which is opposite to the lower end 133, has aback side 134. An end of each fin 11 extends to connect with the backside 134. Thus, At least part of each fin 11 projects from the LED lightboard 3 in an axis. In one example, in an axial direction of the LEDlamp, each of the fins 11 is formed with an extension portion 1101between the back side 134 of the base 13 and the light board 3. Theextension portions 1101 can increase area of heat dissipation of thefins 11 and improve an effect of heat dissipation. In addition, theextension portion 1101 does not increase overall height of the LED lampso as to be advantageous to controlling overall height of the LED lamp.

FIG. 15 is a cross-sectional view of the LED lamp of this embodiment. Asshown, in this embodiment, the back side 134 of the base 13 is slanted.For example, when the LED lamp is being hung, in an inward radialdirection, the back side 134 is upwardly slanted. In another aspect, ina radial direction of the LED lamp toward an axis of the LED lamp, anaxial distance from the back side 134 to the light board 3 isprogressively increased. Such an arrangement is advantageous toconvection air is introduced along the back side 134 to bring out heatof the back side 134 and prevents the back side 134 from obstructing airflowing into.

As shown in FIGS. 2 and 5, in a using status, the light board 3 isdownwardly arranged, a position of the lower end 133 is lower than anend side 44 of the lamp cover 4 and the light output surface 43. As aresult, when packing, transporting or using the LED lamp, if collisionoccurs, then the lower end 133 will collide to prevent the lamp coverfrom colliding to damage the end side 44 or the light output surface 43.

As shown in FIGS. 2 and 5, a receiving space (indent 132) is encompassedby the lower ends 133 for receiving the lamp cover 4. Height of the lampcover 4 received in the receiving space does not project from the lowerend 133. Height of the LED lamp mainly includes height of the lamp shell2, height of the heat sink 1 and height of the lamp cover 4. In thisembodiment, the lamp cover 4 does not project from the lower end 133,this can control overall height of the lamp and the lamp cover 4 doesnot increase overall height of the lamp. In another aspect, the heatsink 1 additionally increases heat dissipating portion (downwardprotruding part of the light board 3 corresponding to the lower end133). In other embodiments, a part of the lamp cover 4 may project fromthe lower end 133.

As shown in FIGS. 2, 4 and 5, a gap is kept between the end side 44 andthe light board 3 to form a room 8. The room 8 communicates with boththe first air inlet 2201 of the first heat dissipating channel 7 a andthe second air inlet 1301 of the second heat dissipating channel 7 b.Air flows into the room 8 through the vent 41 of the end side 44 andthen flows into both the first heat dissipating channel 7 a and thesecond heat dissipating channel 7 b. The room 8 allows air therein tomix and the mixed air is distributed according to negative pressure(resulting from temperature difference) of both the first and secondheat dissipating channels 7 a, 7 b so as to make distribution of airmore reasonable.

In this embodiment, when a passive heat dissipation manner (fanless) isadopted, the ratio of power (W) of the LED lamp to heat dissipatingsurface area (square cm) of the heat sink 1 is 1:20˜30. That is, eachwatt needs heat dissipating surface area of 20˜30 square cm for heatdissipation. Preferably, the ratio of power of the LED lamp to heatdissipating surface area of the heat sink 1 is 1:22˜26. More preferably,the ratio of power of the LED lamp to heat dissipating surface area ofthe heat sink 1 is 1:25. The first heat dissipating channel 7 a isformed in the lamp shell 2, the first heat dissipating channel 7 a hasthe first air inlet 2201 at an end of the lamp shell 2, and another endof the lamp shell 2 has the venting hole 222. Air flows into the firstair inlet 2201 and flows out from the venting hole 222 to bring out heatin the first heat dissipating channel 7 a. The second heat dissipatingchannel 7 b is formed in the fins 11 and the base 13 and the second heatdissipating channel 7 b has the second air inlet 1301. Air flows intothe second air inlet 1301, passes the second heat dissipating channel 7b, and finally flows out from the spaces between the fins 11 to bringout heat radiated from the fins 11 to air therearound and enhance heatdissipation of the fins 11. By both the first and second heatdissipating channels 7 a, 7 b, efficiency of natural convection can beincreased. This reduces required area of heat dissipation of the heatsink 1 so as to make the ratio of power of the LED lamp to heatdissipating area of the heat sink 1 be between 20 and 30. In thisembodiment, overall weight of the LED lamp is less than 1.7 Kg. When theLED lamp is provided with power of about 200 W (below 300 W, preferably,below 250 W), the LED chips 311 are lit up and emit luminous flux of atleast 25000 lumens.

As shown in FIG. 1, weight of the heat sink 1 in this embodimentaccounts for above 50% of weight of the LED lamp. In some embodiments,weight of the heat sink 1 accounts for 55˜65% of weight of the LED lamp.Under this condition, volume of the heat sink 1 accounts for above 20%of volume of the overall LED lamp. Under a condition of the same thermalconductivity of the heat sink 1 (i.e. overall heat sink 1 uses a singlematerial or two different materials with almost identical thermalconductivity), the larger the volume occupied by the heat sink 1 is, thelarger the heat dissipating area which can be provided by the heat sink1 is. As a result, when volume of the heat sink 1 accounts for above 20%of volume of the overall LED lamp, the heat sink 1 may have more usablespace to increase its heat dissipating area. Considering the arrangementspace of the power source 5, the lamp cover 4 and the lamp shell 2,preferably, volume of the heat sink 1 accounts for 20%˜60% of volume ofthe overall LED lamp. More preferably, volume of the heat sink 1accounts for above 25˜50% of volume of the overall LED lamp.Accordingly, although the overall size of the LED lamp is limited andthe space for receiving the power source 5, the lamp cover 4 and thelamp shell 2 must be kept, volume of the heat sink 1 can still bemaximized. This is advantageous to design of overall heat dissipation ofthe LED lamp.

FIG. 16 is top view of the heat sink 1 of the LED lamp of an embodiment.As shown, the heat sink 1 suffers the above volume limit, so at leastpart of the fins 11 are extended outward in a radial direction of theLED lamp with at least two sheets at an interval. By such anarrangement, the fins 11 in a fixed space can have larger area of heatdissipation. In addition, the extended sheets form support to the fins11 to make the fins firmly supported on the base 13 to prevent the fins11 from deflecting.

In detail, as shown in FIG. 16, the fins include first fins 111 andsecond fins 112. The bottoms of both the first fins 111 and the secondfins 112 in an axis of the LED lamp connect to the base 13. The firstfins 111 interlace with the second fins 112 at regular intervals. Beingprojected from the axial direction of the LED lamp, each of the secondfins 112 is to be seen as a Y-shape. Such Y-shaped second fins 112 canhave more heat dissipating area under a condition of the heat sink 1occupying the same volume. In this embodiment, both the first fins 111and the second fins are evenly distributed on a circumference,respectively. Every adjacent two of the second fins 112 are symmetricalabout one of the first fins 111. In this embodiment, an interval betweenone of the first fins 111 and adjacent one of the second fins 112 is8˜12 mm. In general, to make air flow in the heat sink 1 smooth and tomake the heat sink perform a maximum effect of heat dissipation,intervals between the fins 11 should be as uniform as possible.

As shown in FIGS. 9 and 16, at least one of the fins 11 is divided intotwo portions in a radial direction of the LED lamp. Thus, a gap betweenthe two portions forms a passage to allow air to pass. In addition, theprojecting area of the gap directly exactly corresponds to an area thatthe LED chips 311 are positioned on the LED board 3 to enhanceconvection and improve an effect of heat dissipation to the LED chips311. In an aspect of limited overall weight of the LED lamp, part of thefins 11 divided with a gap reduces the amount of the fins 11, decreasesoverall weight of the heat sink 1, and provides a surplus space toaccommodate other elements.

FIG. 17 is an enlarged view of portion E in FIG. 16. As shown in FIGS.16 and 17, the fins 11 include first fins 111 and second fins 112. Eachof the first fins 11 is divided into two portions in a radial directionof the LED lamp, i.e. a first portion 111 a and a second portion 111 b.The two portions are divided with a gap portion 111 c. The first portion111 a is located inside the second portion 111 b in a radial direction.Each of the second fins 112 has a third portion 112 a and a fourthportion 112 b extending therefrom. The fourth portions 112 b are locatedradially outside the third portions 112 a to increase space utilizationand make the fins have more heat dissipating are for heat dissipation.As shown in FIG. 17, the third portion 112 a is connected to the fourthportion 112 b through a transition portion 113. The transition portion113 has a buffer section 113 a and a guide section 113 b. At least oneor both of the buffer section 113 a and the guide section 113 b arearced in shape. In other embodiment, both the buffer section 113 a andthe guide section 113 b are formed into an S-shape or an invertedS-shape. The buffer section 113 a is configured to prevent air radiallyoutward flowing along the second fins 112 from being obstructed to causevortexes. Instead, the guide section 113 b is configured to be able toguide convection air to radially outward flow along the second fins 112without interference (as shown id FIG. 18).

As shown in FIG. 17, one of the second fins 112 includes a third portion112 a and two fourth portion 112 b. The two fourth portions 112 b aresymmetrical about the third portion 112 a. In other embodiments, one ofthe second fins 112 may include a third portion 112 a and multiplefourth portions 112 b such as three or four fourth portions 112 b (notshown). The multiple fourth portions 112 b of the second fin 112 arelocated between two first fins 111.

As shown in FIG. 17, a direction of any tangent of the guide section 113b is separate from the gap portion 111 c to prevent convection air fromflowing into the gap portion 111 c through the guide portion 113 b, suchthat the poor efficiency of heat dissipation caused by longer convectionpaths is able to be avoid as well. Preferably, a direction of anytangent of the guide section 113 b is located radially outside the gapportion 111 c. In other embodiments, a direction of any tangent of theguide section 113 b is located radially inside the gap portion 111 c.

As shown in FIG. 19, in another embodiment, a direction of any tangentof the guide section 113 b falls in the gap portion 111 c to makeconvection more sufficient but convection paths will increase.

As shown in FIG. 14, at least partially of fin 11 has a protrusion 1102projecting from a surface of the fin 11. The protrusions 1102 extendalong an axis of the LED lamp and are in contact with the base 13. Asurface of the protrusion 1102 may selectively adopt a cylindrical shapeor a regular or an irregular polygonal cylinder. The protrusions 1102increase surface area of the fins 11 to enhance efficiency of heatdissipation. In addition, the protrusions 1102 also form a supporteffect to the fins 11 to prevent the fins 11 from being inflected inmanufacture. In some embodiments, a single fin 11 is divided into twoportions in a radial direction of the LED lamp. Each portion is providedwith at least one protrusion 1102 to support the two portions. In thisembodiment, the protrusion 1102 is located at an end portion of each fin11 in a radial direction of the LED lamp, for example, at end portionsof the first portions 111 a, 111 b (the ends near the gap portion 111c).

In some embodiments, when each fin 11 is a single piece without the gapportion, the protrusion 1102 may also be disposed on a surface of eachfin 11 (not shown) to increase surface area of heat dissipation of thefins 11 and have a support effect to the fins 11 to prevent the fins 11from being inflected in manufacture.

FIG. 20 is a bottom view of the LED lamp of FIG. 1 without the lampcover 4. FIG. 21 is an enlarged view of portion A in FIG. 20. As shownin FIGS. 20 and 21, the heat sink 1 is disposed outwardly of the sleeve21, and the power source 5 is disposed in the inner space of the sleeve21. A distance is kept between distal ends of the fins 11 and the sleeve21. Accordingly, the sleeve 21 which has been heated to be thermallyexpanded will not be pressed by the fins 11 to be damaged. Also, heatfrom the fins 11 will not be directly conducted to the sleeve 21 toadversely affect electronic components of the power source 5 in thesleeve 21. Finally, air existing in the distance between the fins 11 andthe sleeve 21 of the lamp shell 2 (as shown in FIG. 3) possesses aneffect of thermal isolation so as to further prevent heat of the heatsink 1 from affecting the power source 5 in the sleeve 21. In otherembodiments, to make the fins 11 have radial support to the sleeve 21,distal ends of the fins 11 may be in contact with an outer surface ofthe sleeve 21 and another part of the fins 11 are not in contact withthe sleeve 21. Such a design may be applied in the LED lamp shown inFIG. 20. As shown in FIG. 20, the light board 3 includes a thirdaperture 32 for exposing both the first air inlet 2201 of the first heatdissipating channel 7 a and the second air inlet 1301 of the second heatdissipating channel 7 b. In some embodiments, to rapidly dissipate heatfrom the power source 5, the ratio of cross-sectional area of the firstair inlet 2201 to cross-sectional area of the second air inlet 1301 isgreater than 1 but less than or equal to 2. In some embodiments, torapidly dissipate heat from the power source 5, the ratio ofcross-sectional area of the second air inlet 1301 to cross-sectionalarea of the first air inlet 2201 is greater than 1 but less than orequal to 1.5.

As shown in FIGS. 14 and 15, the innermost of the fins 11 in a radialdirection of the LED lamp is located outside the venting hole 222 in aradial direction of the LED lamp. In one example, an interval is keptbetween the innermost of the fins 11 in a radial direction of the LEDlamp and the venting hole 222 in a radial direction of the LED lamp. Asa result, heat from the fins 11 flowing upward will not gather to theventing hole 222 to keep an interval with the venting hole 222. Thisavoids heat making air around the venting hole 222 heat up to affectconvection temperature speed of the first heat dissipating channel 7 a(the convection speed depends upon a temperature difference between twosides of the first heat dissipating channel 7 a, when air temperaturenear the venting hole 222 rises, the convection speed willcorrespondingly slowdown.).

FIG. 22 is a cross-sectional view of an LED lamp of an embodiment. FIG.23 is an enlarged view of the LED lamp of portion C in FIG. 22. Asshown, the heat sink 1 includes the fins 11 and the base 13. The base 13has a projecting portion 135 which is downwardly formed in an axialdirection of the LED lamp. The projecting portion 135 protrudes from thelight board 3 in an axial direction of the LED lamp. The lowermostposition of the projecting portion 135 (lower end 133) is substantiallyflush with the light output surface 43 of the light cover 4 (in an axialdirection of the LED lamp) or the lowermost position of the projectingportion 135 slightly protrudes from the light output surface 43. Forexample, the lowermost position of the projecting portion 135 protrudesfrom the light output surface 43 by about 1˜10 mm to keep overall heightof the heat sink 1 in the LED lamp unvarying or slightly increase volumefor obtaining more heat dissipating area of both the fins 11 and thebase 13.

The projecting portion 135 in this embodiment is configured to beannular and a concave structure is defined by both the projectingportion 135 and the base 13 for receiving and protecting both the lightsource and the light cover 4. Also, the concave structure can perform aneffect of anti-flare (because the concave structure shades lateral lightfrom the light source).

As shown in FIG. 23, the base 13 has a first inner surface 136 and thelamp cover 4 has a peripheral wall 45. When the lamp cover 4 has beencorrectly installed to the LED lamp, the first inner surface 136corresponds to the peripheral wall 45 (the outer wall of the lamp cover4). A gap is kept between the first inner surface 136 and the peripheralwall 45 to prevent the lamp cover 4 from thermally expanding and beingpressed by the first inner surface 136 to be damaged. The gap betweenthe first inner surface 136 and the peripheral wall 45 can reduce oravoid the abovementioned pressing. In other embodiments, a part of theperipheral wall 45 is in contact with the first inner surface 136 toradially support the lamp cover 4 by the first inner surface 136. Gapsare still kept between the other parts of the peripheral wall 45 and thefirst inner surface 136.

As shown in FIG. 23, the first inner surface 136 is configured to be aslant and an angle is formed between the first inner surface 136 and thelight board 3. The angle may be an obtuse angle. Thus, when the lampcover 4 is thermally expanded and its peripheral wall 45 presses theslant, the pressure exerted from the first inner surface 136 to an outerportion of the lamp cover 4 is divided into a downward component and ahorizontal component to reduce horizontal pressure to the lamp cover 4(horizontal pressure is a main cause of damage). In other embodiments,the peripheral wall 45 may abut against the first inner surface 136 (notshown) so as to support or limit the lamp cover 4. Also, because thefirst inner surface 136 is a slant, damage of the lamp cover 4 resultingfrom pressure of thermal expansion can be decreased. An end portion ofthe peripheral wall 45 may abut against the first inner surface 136 todecrease contact area between overall peripheral wall 45 and the base 13and avoid excessive thermal conduction.

As shown in FIG. 23, the base further includes a second inner surface137 and the lamp cover 4 has a peripheral wall 45. A gap is kept betweenthe peripheral wall 45 and the first inner surface 136. An end portionof the peripheral wall 45 abuts against the second inner surface 137. Anangle between the first inner surface 136 and the light board 3 is lessthan an angle between the second inner surface 137 and the light board3. That is, the second inner surface 137 is flatter than the first innersurface 136. As a result, when the peripheral wall 45 abuts against thesecond inner surface 137 and the lamp cover 4 is thermally expanded, thehorizontal pressure from the second inner surface 137 to the lamp cover4 becomes less. In this embodiment, the angle between the second innersurface 137 and the light board 3 is between 120 degrees and 150degrees. If the angle is too big, then radial support to the lamp cover4 in a radial direction of the LED lamp will not be sufficient enough.While if the angle is too small, not only can the horizontal pressureexerted to the lamp cover 4 which has been thermally expanded not bereduced, but also limiting and supporting the lamp cover 4 in an axialdirection of the LED lamp cannot be obtained. When the angle falls inthe above range, a great balance can be accomplished. In otherembodiments, both the second inner surface 137 and the first innersurface 136 may be curved. A distance difference between the secondinner surface 137 and the axis of the LED lamp and between the firstinner surface 136 and the axis of the LED lamp downward progressivelyincreases. However, in general, the second inner surface 137 is flatterthan the first inner surface 136.

As shown in FIG. 24, the end portion of the peripheral wall 45 isprovided with protruding plates 451 upward extending from the peripheralwall 45 at regular intervals. The protruding plates 451 are the partsthat the end portion of the peripheral wall 45 is in actual contact withthe second inner surface 137. The protruding plates 451 can reducecontact area between the peripheral wall 45 and the base 13 to preventheat of the heat sink 1 from being conducted to the lamp cover 4 to makethe lamp cover 4 overheat.

As shown in FIGS. 22 and 23, a gap is formed between the peripheral wall45 and the base 13 and the base 13 is formed with a hole. A side of thehole communicates with the gap and the other side corresponds to thefins 11. In one example, air may flow into the gap, passes the hole andreaches the fins 11 to enhance convection. The convection path as shownby the arrow in FIG. 23 may form a fourth heat dissipating channel 7 dof the LED lamp in this embodiment. Because the protruding plates 451are arranged on the peripheral wall 45 at regular intervals, air canpass through intervals between the protruding plates 451 (as shown inFIG. 24) to accomplish the abovementioned convection.

The heat sink 1 in this embodiment is an integrated structure so as toadvantageous to reducing thermal resistance between the fins 11 and thebase 13. In other embodiments, in order to be convenient to be machinedand formed, the fins 11 and the base 13 may also be configured to bedetachable.

LEDs generate heat while they are emitting. A key parameter inconsidering of thermal conduction of LEDs is thermal resistance. Thesmaller the thermal resistance is, the better the thermal conduction is.Primarily, factors of thermal resistance include length of conductionpath, conduction area and thermal conductivity of a thermo-conductivematerial. It can be expressed by the following formula:Thermal resistance=length of conduction path L/(conduction areaS*thermal conductivity)

That is to say, the shorter the conduction path is and the larger theconduction area is, the lower the thermal conductivity is.

As shown in FIG. 20, in this embodiment, the light board 3 includes atleast one LED chip set 31 having LED chips 311.

As shown in FIG. 20, in this embodiment, the light board 3 is dividedinto three areas comprising an inner ring, a middle ring and an outerring. All the LED chip sets 31 are located in the three areas. In oneexample, the inner ring, the middle ring and the outer ring areseparately mounted by different amount of LED chip sets 31. In anotheraspect, the light board 3 includes three LED chip set 31. The three LEDchip sets 31 are respectively located in the inner ring, the middle ringand the outer ring. Each of the LED chip sets 31 separately in the innerring, the middle ring and the outer ring has at least one LED chip 311.

Four hypothetical circle lines are defined on the light board 3 as shownin FIG. 20. The outer ring is defined by the area between the outermosttwo circle lines of the four, the inner ring is defined by the areabetween the innermost two circle lines of the four, and the middle ringis located between the two areas mentioned above. In another embodiment,the light board 3 is separated into two rings (areas), and the chip sets31 are divided to be mounted on the two rings.

As shown in FIG. 20, several LED chips 311 in a circle or approximatelyin a circle compose an LED chip set. There are several LED chip sets 31on the light board 3. In a single LED chip set 31, a center distancebetween two adjacent LED chips 311 is L2. A center distance between anyLED chip 311 of any LED chip set 31 and the nearest LED chip 311 of anadjacent LED chip set 31 is L3. The ratio of L2 to L3 is 1:0.8˜2,preferably, L2:L3 is 1:1˜1.5. This makes distribution of the LED chips311 so even to accomplish an object of even light output.

FIG. 25 is a schematic view of the combination of the fins 11 and theLED chips 311 of one embodiment. As shown in FIGS. 20 and 25, in thisembodiment, when at least one fin 11 is projected onto the plane onwhich the LED chip sets 31 are located along the axial direction of theLED lamp, a projection of the fin 11 at least touches at least one LEDchip 311 of the LED chip set 31. In detail, when at least one fin 11 isprojected onto a plane on which the LED chip set 31 is located along theaxial direction of the LED lamp, a projection of the fin 11 at leasttouches at least one LED chip 311 of the LED chip set 31 in the innerring, the middle ring or the outer ring. As shown in FIG. 25, theprojection of the fin 11 touches an LED chip 311. As indicated by thearrow in the figure, it is a heat dissipating path of the LED chip 311and the fin 11. As shown in FIG. 26, the projection of the fin 41 doesnot touch the LED chip 311 in the figure. As indicated by the arrow inthe figure, it is a heat dissipating path of the LED chip 311 and thefin 11. It can be seen that the heat dissipating path of the latter islonger than the former's. As a result, by means of a projection of a finat least touching at least one LED chip 311 of the LED chip set 31 inthe inner ring, the middle ring or the outer ring, a heat dissipatingpath of the LED chip 311 can be shortened. This can reduce thermalresistance to be advantageous to thermal conduction. Preferably, a fin11 is projected onto a plane on which the LED chip set 31 is locatedalong the axial direction of the LED lamp, a projection of any fin 11(the first fin 111 or the second fin 112) at least touches at least oneLED chip 311 of the LED chip set 31.

In this embodiment, the LED chip sets 31 in outer rings corresponding tothe fins 11 are greater than the LED chip sets 31 in inner rings innumber. Here the term “corresponding to” means projection relationshipin the axial direction of the LED lamp, for example, when the LED chipsets 31 in outer rings are projected onto the fins 11 in the axialdirection of the LED lamp, the fins 11 to which the LED chips 31 inouter rings correspond are located on a relatively outer portion of theheat sink 1. Here the LED chip sets 31 in outer rings have more LEDchips 311 in number, so they need more fins 11 (area) to implement heatdissipation.

As shown in FIGS. 1 and 20, the light board 3 has an inner border 3002and an outer border 3003. Both the inner border 3002 and the outerborder 3003 separately upward extend along the axial direction of theLED lamp to form a region. An area of part of the fins 11 inside theregion is greater than an area of part of the fins 11 outside theregion. As a result, the most of the fins 11 can correspond to the lightboard 3 (a shorter heat dissipating path) to enhance heat dissipatingefficiency of the fins 11 and increase effective area of heat conductionof the fins 11 to the LED chips 311.

As shown in FIGS. 3, 5 and 20, a reflecting region 3001 is disposed in aregion between the inner ring and an outer edge of the light board 3 toreflect the upward light to the light output surface 43. This can reduceloss of light in an opposite direction of light output in the axialdirection of the LED lamp to increase overall intensity of light output.

As shown in FIGS. 4 and 20, the light board 3 is formed with a thirdaperture 32 separately communicating with the first heat dissipatingchannel 7 a and the second heat dissipating channel 7 b. For example,the third aperture 32 communicates with spaces between the fins 11 andthe chamber of the lamp shell 2 to form air convection paths between thespaces between the fins 11 and between the chamber of the lamp shell 2and the outside of the Led lamp. The third aperture 32 is located insidethe inner ring of the LED lamp. Thus, it would not occupy the space ofthe reflecting region 3001 to affect reflective efficiency. In detail,the third aperture 32 is located at a central region of the light board3 and both the first air inlet 2201 and the second air inlet 1301 makeair intake through the same aperture (the third aperture 32). In oneexample, after convection air passes through the third aperture 32, andthen enters the first air inlet 2201 and the second air inlet 1301. Thethird aperture 32 is located at a central region of the light board 3,so both the first air inlet 2201 and the second air inlet 1301 cancommonly use the same air intake. Thus, this can prevent occupying anexcessive region of the light board 3 and prevent the usable regionalarea of the light board 3 for disposing the LED chips 311 fromdecreasing due to multiple air intakes. On the other hand, the sleeve 21corresponds to the third aperture 32, so convection air may have aneffect of thermal isolation to prevent temperatures inside and outsidethe sleeve 21 from mutually affecting each other when air enters. Inother embodiments, if both the first air inlet 2201 and the second airinlet 1301 are located at different positions, then the third aperture32 may be multiple in number to correspond to both the first air inlet2201 and the second air inlet 1301.

As shown in FIG. 20, in an embodiment, in the inner ring, both adjacenttwo of the LED chips 311 and the axis of the LED lamp form a centerangle A; in the middle ring, both adjacent two of the LED chips 311 andthe axis of the LED lamp form a center angle B. The center angle B isless than the center angle A in degree. In the outer ring, both adjacenttwo of the LED chips 311 and the axis of the LED lamp form a centerangle C, and the center angle C is less than the center angle B indegree. For example, the LED chips 311 in the outer ring are more thanthose in the middle ring in number. Thus, a distance between adjacenttwo of the LED chips 311 in the outer ring is not much greater than adistance between adjacent two of the LED chips 311 in the middle ring,even, the two distances may be similar or identical. As a result, bothdistribution of the LED chips 311 and light output will be very even. Inone example, the LED chip sets 31 are multiple in number and areannularly mounted on the light board 3. A center angle formed byadjacent two of the LED chips 311 in an inner portion and the axis ofthe LED lamp is greater than a center angle formed by adjacent two ofthe LED chips 311 in an outer portion and the axis of the LED lamp. Thatis, The LED chips 311 of outer LED chip sets 31 are greater than the LEDchips 311 of inner LED chip sets 31 in number such that a distancebetween adjacent two of the LED chips 311 of outer LED chip sets 31 isless than a distance between adjacent two of the LED chips 311 of innerLED chip sets 31. As a result, both distribution of the LED chips 311and light output will be very even.

As shown in FIG. 25, in one embodiment of the present invention, thelight board 3 is provided with an insulative layer 34 with highreflectivity. The insulative layer 34 may adopt thermal grease. Theinsulative layer 34 is smeared on the light board 3 to an edge thereof.A distance between the LED chips 311 at the outermost position and anedge of the light board 3 is greater than 4 mm. Preferably, a distancebetween the LED chips 311 at the outermost position and an edge of thelight board 3 is greater than 6.5 mm but less than 35 mm. In addition, acreepage distance between the outermost LED chips 311 and the heat sink1 can be guaranteed to prevent arc occurring between the LED chips 311and the heat sink. In addition, the insulative layer 34 may also have aneffect of thermal isolation to prevent overheating and deformation ofthe lamp cover 4.

FIG. 27 is a schematic view of the light board 3 in this embodiment. Asshown in FIG. 27, in this embodiment, the LED chip sets 31 are at leasttwo in number. The at least two LED chip sets 31 are annularly arrangedon the light board 3 in order. Each LED chip set 31 includes at leastone LED chip 311. Each LED chip 311 of one of the LED chip sets 31 onthe light board 3 is radially interlacedly arranged with any one LEDchip 311 of adjacent one of the LED chip sets 31 on the light board 3.That is, the LED chips 311 of different LED chip sets 31 are located indifferent directions in a radial direction of the LED lamp. In oneexample, if any line starting with the axis of the LED lamp andextending toward a radial direction of the LED lamp cuts two or more ofthe LED chips 311, then it will cut different positions of these two ormore LED chips 311 and will not cut the same positions of these two ormore LED chips 311. As a result, if there is convection on the lightboard 3 and air radially flows on the light board 3, the contact betweenair and the LED chips 311 will be more sufficient and a better effect ofheat dissipation will be obtained because of the airflow paths. Inaddition, in the aspect of lighting effect, such distribution of the LEDchips 311 is more advantageous to uniformity of light output.

In this embodiment, an open region 312 is formed between adjacent two ofthe same LED chip set 31 to allow air to flow between the LED chips 311to bring out heat generated from the working LED chips 311. The openregion 312 between any two adjacent LED chips 311 of one of adjacent twoof the chip sets 31 on the light board 3 interlaces to and communicateswith the open region 312 between any two adjacent LED chips 311 ofanother one of the chip sets 31 on the light board 3 in a radialdirection of the LED board 3. As a result, if there is convection on thelight board 3 and air radially flows on the light board 3, the contactbetween air and the LED chips 311 will be more sufficient and a bettereffect of heat dissipation will be obtained because of the airflowpaths. If both the open region 312 between any two adjacent LED chips311 of one of adjacent two of the chip sets 31 on the light board 3 andthe open region 312 between any two adjacent LED chips 311 of anotherone of the chip sets 31 on the light board 3 of the LED board 3 are inthe same radial direction, then air will flow along radial directions ofthe light board 3. The contact between air and the LED chips 311 willdecrease to be disadvantageous to heat dissipation of the LED chips 311because of the airflow paths.

For example, three LED chip sets 31 are annularly disposed along aradial direction of the light board 3 in order, any open regions 312 ofthe three LED chips 31 are not in the same direction in a radialdirection. Thus, convection paths on the light board 3 can be optimizedto increase efficiency of the heat dissipation.

In some applications, when LEDs are emitting, a light distributionregion will be formed under the LED lamp. This means distribution ofintensity of light source. The design of the LED lamp aims forconcentrating the light distribution region to a specific zone toincrease local intensity.

FIGS. 28A-28C are perspective views of the power source 5 of oneembodiment at different viewpoints. FIG. 28d is a main view of the powersource 5 of one embodiment. The power source 5 is electrically connectedto the LED chips 311 to power the LED chips 311. As shown in FIGS.28A-28C, the power source 5 includes a power board 51 and a plurality ofelectronic components mounted thereon.

As shown in FIG. 28C, a transformer 54 in the electronic componentsincludes a core 541 and coils 542. The core 541 has a room in which thecoils 542 are received. The room has an opening in the axial directionof the LED lamp so as to make heat generated from the coils 542 and thecore 541 move upward. Also, the heat dissipating direction of thetransformer 54 is consistent with the convection path of the first heatdissipating channel 7 a (as mentioned in the description of FIG. 4) forbeing advantageous to heat dissipation.

As shown in FIGS. 28B and 28C, the room is provided with two openings attwo ends in the axial direction of the LED lamp to increase heatdissipating effect to the coils 542. In addition, after the coils 542are installed in the room of the core 541, a gap is kept between thecoils 542 and the room to allow air to flow. This can further increaseheat dissipating effect to the coils 542.

As shown in FIG. 28B, the transformer 54 has a first side 5401 and asecond side 5402, both of which are perpendicular to the power board.The first side 5401 is perpendicular to the axial direction of the lamp.The first side 5401 is less than the second side 5402 in area. Thus,such an arrangement of the small side can reduce resistance toconvection of the first heat dissipating channel 7 a.

As shown in FIG. 28C, the electronic components include at least oneinductor 55 including an annular core 551. A coil is wound around theannular core 551 (not shown). An axis of the annular core 551 isparallel to the axis of the LED lamp to make the coil have larger areato be in contact with convection air. This can further increase heatdissipating effect to the inductor 55. In addition, a shape of theannular core 551 corresponds to the convection path of the first heatdissipating channel 7 a. Thus, convection air can pass through theinside of the annular core 551 to further increase heat dissipatingeffect to the inductor 55.

As shown in FIGS. 28A and 28B, heat-generating elements in theelectronic components include integrated circuits (ICs) 56, diodes,transistors, the transformer 54, the inductor 55 and resistors. Theseheat-generating elements are separately mounted on the power board 51 todistribute heat-generating sources and prevent local high temperature.In addition, the heat-generating elements may be mounted on differentsurfaces of the power board 51 to perform heat dissipation. At thistime, the heat-generating elements are in contact with correspondingheat dissipating elements.

As shown in FIGS. 28A and 28B, at least one IC 56 is arranged to bemounted on different surface as other heat-generating elements arearranged of the power board 51. As a result, the heat-generating sourcescan be separated to avoid local high temperature and influence to the IC56 from the other heat-generating elements.

As shown in FIGS. 28A and 28B, in a direction perpendicular to the powerboard 51 (i.e. projection relationship in a direction perpendicular tothe power board 51), the IC 56 does not overlap any heat-generatingelements to avoid heat accumulation.

As shown in FIG. 15, the power board 51 is parallel to the axis of theLED lamp. Thus, in the axial direction of the LED lamp, the power board51 is divided into an upper portion and a lower portion. Arrangingspaces of both the upper portion and the lower portion are identical orapproximately identical to form better layout of the electroniccomponents. Besides, if the power board 51 inclines toward the axis ofthe LED lamp, then air flow may be obstructed and it is disadvantageousto heat dissipation of the power source 5.

As shown in FIGS. 1 and 15, the power board 51 divides the lamp shell 2into a first portion 201 and a second portion 202. Area of the ventinghole 222 corresponding to the first portion 201 is greater than area ofthe venting hole 222 corresponding to the second portion 202. Thus, whenimplementing layout of electronic components, most or all of electroniccomponents or some thereof which generate a large amount of heat such asinductors, resistors, transformers, rectifiers or transistors may bedisposed in the first portion 201.

As shown in FIG. 15, the power board 51 divides an inner chamber of thelamp shell 2 into a first portion 201 and a second portion 202. Thefirst portion 201 is greater than the second portion 202 in volume. Whenimplementing layout of electronic components, most or all of electroniccomponents or some thereof which generate a large amount of heat such asinductors, resistors, transformers, rectifiers or transistors may bedisposed in the first portion 201.

Please simultaneously refer to FIGS. 15 and 20, further, area of firstair inlet 2201 corresponding to the first portion 201 is greater thanarea of the second air inlet 2202 corresponding to the second portion202. Thus, more air can flow into the first portion 201 to perform heatdissipation to the electronic components. Here, the specific descriptionof the air inlet is that the first air inlet 2201 is divided into twoportions by the power board 51, one of the two portions corresponds tothe first portion 201 and the other one of the two portions correspondsto the second portion 202 so as to make more air flow into the first airinlet 2201 and enter the first portion 201.

As shown in FIG. 15, the electronic components 501 includeheat-generating elements 501. At least one of the heat-generatingelements 501 is adjacent to the lamp head 23 through which heat isdissipated without occupying resource of heat dissipation of the firstheat dissipating channel 7 a. The at least one heat-generating element501 abovementioned is an inductor, a resistor, a rectifier or a controlcircuit.

As shown in FIG. 15, heat of the at least one heat-generating element istransferred to the lamp head 23 through thermal conduction or radiationand dissipated to air through the lamp head 23.

As shown in FIG. 15, the at least one heat-generating element 501 is inthermal contact with the lamp head 23. In detail, the at least oneheat-generating element 501 is located in the lamp head 23. Theheat-generating element 501 is in contact with the lamp head 23 througha thermal conductor 53 and the heat-generating element 501 is fastenedto the lamp head 23 through the thermal conductor 53. Therefore, thethermal conductor not only performs an effect of heat transfer but alsofixes the heat-generating element 501 to avoid loosening of theheat-generating element 501. The phrase “the heat-generating element 501is located in the lamp head 23” means both the lamp head 23 and theheat-generating element 501 have an overlapping area in a projectionperpendicular to the axis of the LED lamp.

As shown in FIG. 15, the thermal conductor 53 is disposed in the lamphead 23 through filling to implement connection between the lamp head 23and the heat-generating element 501. The thermal conductor 53 onlycloaks an end portion of the power source 5 and is higher than theventing 222 in position to prevent overweight resulting from the thermalconductor 53. Additionally, the thermal conductor 53 adopts aninsulative material to guarantee safety and prevent the electroniccomponents and metal portion 231 of the lamp head 23 from being incontact. In other embodiments, the thermal conductor 53 may also be awire connecting the power source 5 to the lamp head 23 (not shown).

As shown in FIG. 15, the lamp head 23 includes the metal portion 231,which is in thermal contact with the thermal conductor 53. That is, atleast part of an inner side of the metal portion 231 constitutes a wallof the inner chamber of the lamp shell 2 to make the thermal conductordirectly connect with the metal portion 231 and perform heat dissipationby the metal portion 231. Part of the metal portion 231 would performheat dissipation through air, and another part of the metal portionwould perform heat dissipation through a lamp socket connecting to themetal portion 231.

As shown in FIGS. 2 and 28A, in this embodiment, at least one of theelectronic components of the power source 5, which is the most adjacentto the first air inlet 2201 of the first heat dissipating channel 7 a isa heat intolerance component, such as a capacitor, especially for anelectrolytic capacitor. This arrangement can avoid overheating of theheat intolerance component to affect its performance.

In addition, to reduce influence of an electrolytic capacitor 502suffering heat from the heat-generating elements, a surface of theelectrolytic capacitor can be provided with an anti-radiation layer or athermo-isolation layer (not shown). The thermos-isolation layer mayadopt existing plastic material, and the anti-radiation layer may adoptexisting paint, silver plate layer, aluminum foil or otheranti-radiation materials.

As shown in FIG. 28A, in this embodiment, at least part of at least oneof the electrolytic capacitors 502 is not located within the power board51, i.e. at least part of the electrolytic capacitor exceeds the powerboard 51 in the axial direction of the LED lamp. Under a condition ofthe same number of the electronic components, length and material costof the power board 51. In addition, this can make the electrolyticcapacitor further adjacent to the first air inlet 2201 to ensure theelectrolytic capacitor to be located in a relatively low temperaturearea.

As shown in FIG. 15, a position of at least one of the heat-generatingelements 501 in the axial direction of the LED lamp is higher than aposition of the venting hole 222. Most heat of the heat-generatingelement 501 higher than the venting hole 222 is dissipated through thelamp head 23 or other paths. Thus, most heat therefrom is not dissipatedthrough the venting hole 222, and convection speed of the first heatdissipating channel 7 a would not be affected. The heat-generatingelement is an IC, a transistor, a transformer, an inductor, a rectifieror a resistor.

As shown in FIG. 15, the power board 51 is divided into an upper partand a lower part in the axial direction of the LED lamp. Heat-generatingelements are arranged in both the upper part and the lower part. Atleast one of the heat-generating elements in the upper part is locatedabove the venting hole 222 to lower the temperature of the upper partnear the venting hole 222. This can increase an air temperaturedifference between two venting holes 222 in the upper part and the lowerpart to enhance convection.

As shown in FIGS. 2, 3 and 28A, when the power board 51 is assembled inthe lamp shell 2, it has a first portion in the lamp neck 22 and asecond portion in the sleeve 21. The second portion more adjacent to thefirst air inlet 2201 of the first heat dissipating channel 7 a than thefirst portion. Because of such an arrangement, convention air will reachthe second portion first. That is, the second portion is better than thefirst portion in an effect of heat dissipation. Thus, at least part ofheat intolerance elements (e.g. electrolytic capacitors or otherelements which is sensitive to high temperature) should be disposed inthe second portion. Preferably, all electrolytic capacitors are disposedin the second portion. The power board 51 of the second portion isgreater than the first portion in area, so the power board 51 of thesecond portion has more space for accommodating electronic components tobe advantageous to more heat intolerance elements being disposed in thesecond portion. In this embodiment, heat intoleranceelements/thermosensitive elements may be separately mounted on twoopposite sides of the second portion. In other embodiments, hotterelectronic components may be disposed in the second portion (e.g.transformers, inductors, resistors, ICs or transistors) for better heatdissipation.

FIG. 29 is a schematic view of an embodiment of the power source 5,which can be applied to the power source 5 of the LED lamp shown in FIG.4. As shown in FIG. 29, in some embodiments, the power board 51 isdivided into a first mounting zone 511 and a second mounting zone 512 byan axis X. The axis X is between the first mounting zone 511 and thesecond mounting zone 512 as a border. Total weight of the electroniccomponents on the second mounting zone 512 is greater than total weightof the electronic components on the first mounting zone 51. The firstmounting zone 511 is provided with a counterweight 52 to balance the twozones 511, 512 of the power board 51 in weight. This can preventunbalanced weight of the two zones 511, 512 of the power board 51 andprevent the hung LED lamp from tilting because of unbalanced weight.

FIG. 30 is a main view of the counterweight 52 of FIG. 29. FIG. 31 is aside view of FIG. 30. As shown in FIGS. 30 and 31, in some embodiments,the counterweight 52 is a heat dissipating element with heat dissipatingfunction and is disposed on the power board 51. In some embodiments, theheat dissipating assembly has fins 521 for increasing heat dissipatingarea. The counterweight 52 is made of metal with high thermoconductivitysuch as aluminum or copper. In this embodiment, the fins 521 areextendedly arranged along the axial direction of the LED lamp. A channelis formed between two adjacent fins 521 as an air passage. Such anarrangement can increase heat dissipating area of the counterweight 52.In one embodiment, the counterweight 52 includes a long side and a shortside. The channels are parallel with the long side and the long side isconfigured to be parallel with the axis of the LED lamp or substantiallyparallel with the direction of airflow to make the air flow smoothly.

As shown in FIG. 29, the electronic components include heat-generatingelements which generate heat when working. At least one heat-generatingelement is adjacent to a heat dissipating assembly to dissipate part ofheat through the heat dissipating assembly. Preferably, transformers,inductors, resistors, diodes, transistors or ICs of the heat-generatingelements are adjacent to the heat dissipating assembly. More preferably,transformers, inductors, resistors, diodes, transistors or ICs of theheat-generating elements are in direct contact with the heat dissipatingassembly.

In one embodiment of the present invention, two opposite sides of thecircuit board all comprise the counterweight 52, such that the heatdissipating efficiency of the circuit board 51 and the weight balancebetween two sides of the circuit board 51 can be improvedsimultaneously.

As shown in FIG. 29, in some embodiments, the power board 51 is dividedinto a first mounting zone 511 and a second mounting zone 512 by an axisX. The axis X is between the first mounting zone 511 and the secondmounting zone 512 as a border. The second mounting zone 512 is greaterthan the first mounting zone 511 in number of electronic components tomake airflow of the first mounting zone 511 smooth and to reduceobstruction of the electronic components. In this embodiment, both thefirst mounting zone 511 and the second mounting zone 512 haveheat-generating elements to distribute heat sources.

As shown in FIGS. 4, 29 and 32, in some embodiments, the first heatdissipating channel 7 a includes an inner channel 7 a 1 and an outerchannel 7 a 2. The outer channel 7 a 2 is formed between the electroniccomponents on an edge of the power board 51 and an inner wall of theinner chamber of the lamp shell 2. The inner channel 7 a 1 is formed ingaps between the electronic components. This arrangement can enhance aneffect of heat dissipation of the power source 5. In detail, the powerboard 51 in FIG. 29 is divided into two portions (a left portion and aright portion, not necessarily symmetrical), namely, a first portion anda second portion. Both the first portion and the second portion haveelectronic components. The outer channel 7 a 2 is formed between theelectronic components on both the first portion and the second portionand the inner wall of the lamp shell 2. The inner channel 7 a 1 isformed between the electronic components separately on the first portionand the second portion. In this embodiment, a transformer 54 of theelectronic components includes a core 541 and coils 542. The core 541has a chamber in which the coils 542 are disposed. An opening is formedat a side of the chamber in a radial direction to expose the coils 542.The opening corresponds to the inner channel 7 a 1 or the outer channel7 a 2 to make heat from the coils 542 is rapidly ejected throughconvection in the inner channel 7 a 1 or the outer channel 7 a 2.Preferably, two openings are separately formed at two sides of thechamber in a radial direction. One of the two openings corresponds tothe inner channel 7 a 1 and the other one thereof corresponds to theouter channel 7 a 2 to further enhance heat dissipation of thetransformer.

As shown in FIGS. 1, 2, 3 and 4, the lamp shell 2 includes the lamp head23, the lamp neck 22 and the sleeve 21. The lamp head 23 connects to thelamp neck 22 which connects to the sleeve 21. The sleeve 21 is locatedin the heat sink 1 (in the axial direction of the LED lamp, all or mostof the sleeve 21, for example, at least 80% of height of the sleeve 21,does not exceed the heat sink 1). The lamp neck 22 projects from theheat sink 1. Both the sleeve 21 and the lamp neck 22 can providesufficient space to receive the power source 5 and perform heatdissipation, especially for the power source 5 of a high power LED lamp(in comparison with a low power LED lamp, a power source of a high powerLED lamp has more complicated composition and larger size). The powersource 5 is received in both the lamp neck 22 and lamp head 23. Totalheight of the lamp neck 22 and the lamp head 23 is greater than heightof the heat sink 1 so as to provide more space for receiving the powersource 5. The heat sink 1 is separate from both the lamp neck 22 and thelamp head 23 (not overlap in the axial direction, the sleeve 21 isreceived in the heat sink 1). Thus, the power source 5 in both the lampneck 22 and the lamp head 23 is affected by the heat sink 1 slightly(heat of the heat sink 1 would not be conducted to the lamp neck 22 andthe lamp head 23 along a radial direction). In addition, theconfiguration of height of the lamp neck 22 is advantageous to thechimney effect of the first heat dissipating channel 7 a to guaranteeconvection efficiency of the first heat dissipating channel 7 a. Inother embodiments, height of the lamp neck 22 is at least 80% of heightof the heat sink 1 to accomplish the above function. The sleeve 21 ismade of a thermo-isolated material to prevent mutual influence of heatfrom the fins and the power source.

As shown in FIG. 2, the second air inlet 1301 is located in a lowerportion of the heat sink 1 and radially corresponds to an inner side orthe inside of the heat sink 1, i.e. the second air inlet 1301 radiallycorresponds to the inner side or the inside of the fins 11. The innerside or the inside of the fins 11 corresponds to an outer wall (aradially inner side of the fins 11, which nears or abuts against thesleeve 21) of the sleeve 21 of the lamp shell 2. Thus, after convectionair flows into the second air inlet 1301, it flows upward along theouter wall of the sleeve 21 to perform convection and radiallydissipates heat in the inner side or the inside of the fins 11 and theouter wall of the sleeve 21 to implement an effect of thermal isolation.That is, this can prevent heat of the heat sink 1 is conducted from theouter wall of the sleeve 21 to the inside of the sleeve 21 not to affectthe power source 5. From the above, the second heat dissipating channel7 b can not only enhance heat dissipation of the fins 11, but alsoimplement an effect of thermal isolation. Make a positional comparisonbetween the second air inlet 1301 and the LED chips 311, the second airinlet 1301 is located radially inside all of the LED chips 311.

FIG. 34 is an enlarged view of portion B in FIG. 2. As shown in FIG. 34,the lamp head 23 includes a metal portion 231 and an insulative portion232. Wires of the power source 5 penetrate through the insulativeportion 232 to connect with an external power supply. The metal portion231 connects to the lamp neck 22. In detail, as shown in FIG. 35, aninner surface of the metal portion 231 is provided with a thread throughwhich the lamp neck 22 can be screwed on with the metal portion 231.While the metal portion 231 is dissipating heat generated from the powersource 5 in the lamp shell 2 (as described in the above embodiment, atleast part of the inner wall of the metal portion 231 forms a wall ofthe inner chamber of the lamp shell 2, so the thermal conductor directlyconnects with the metal portion 231 and the metal portion 231 can beused for heat dissipation), an outer surface of the metal portion 231 isformed with a projecting structure 2311 as shown in FIG. 35 to addsurface area of the outer surface of the metal portion 231 and enlargeheat dissipating area of the metal portion 231 to increase efficiency ofheat dissipation. As for the power source 5, at least part of the powersource 5 is located in the lamp head 23, and at least part of heatgenerated from the power source 5 can be dissipated through the lamphead 23. The inner wall of the metal portion 231 may also be formed witha projecting structure to add surface area of the inner chamber of thelamp shell 2. In this embodiment, the projecting structure can beimplemented by forming a thread on the inner surface of the metalportion 231.

As shown in FIG. 22, the sleeve 21 has a second stopping portion 215corresponding to the power board 51 for limiting downward movement ofthe power board 51 in the axial direction. Both the first stoppingportion 226 and the second stopping portion 215 limit two sides of thepower board 51 in the axial direction to fasten the power board 51 inthe axial direction.

As shown in FIGS. 1 and 22, the lamp shell 2 has an airflow limitingsurface 214 which extends radially outwardly and is located away fromthe venting hole 222. The airflow limiting surface 214 cloaks at leastpart of the fins 11. When the fins are dissipating heat, hot airflowheated by the part of fins 111 cloaked by the airflow limiting surface214 rises but is blocked by the airflow stopping surface 214 to changeits direction (outward along the airflow stopping surface 214). Thus,rising hot airflow is forced to go away from the venting hole 222. Thiscan prevent hot air from both gathering around the venting hole 222 andaffecting convection speed of the first heat dissipating channel 7 a.Also, this arrangement can prevent rising hot air from both being incontact with the metal portion 231 of the lamp head 23 and affectingheat dissipation of the metal portion 231. Even hot air directly passingthe metal portion 231 to conduct into the inner chamber of the lampshell 2 can also be avoided. The airflow stopping surface 214 may beformed on the sleeve 21. As shown in FIG. 10, in another embodiment ofthe present invention, the airflow stopping surface 214 may also beformed on the lamp neck 22.

As shown in FIG. 22, in this embodiment, upper portions of at least partof the fins 11 in the axial direction of the LED lamp correspond to theairflow stopping surface 214. When the lamp shell 2 is inserted into theheat sink 1, the airflow stopping surface 214 will have a limitingeffect to the lamp shell 2. In this embodiment, the fins abut againstthe airflow stopping surface 214.

As shown in FIG. 22, in this embodiment, the sleeve 21 is made of amaterial whose thermal conductivity is less than that of the material ofwhich the lamp neck 22 is made. The airflow stopping surface 214 isformed on the sleeve 21. Height of the heat sink 1 in the axialdirection does not exceed the airflow stopping surface 214 to reducecontact area between the heat sink 1 and the lamp neck 22. As for thesleeve 21, the lower its thermal conductivity is, the less the heatconducted from the heat sink 1 to the inside of the sleeve 21 is, andthe less the influence to the power source 5 is. As for the lamp neck22, the less the contact area between the lamp neck 22 and the heat sink1 is, the lower the thermal conductivity is. The lamp neck 22 has betterthermal conductivity than that of the sleeve 21. The lamp neck 22 candissipate at least part of heat from the power source 5. In otherembodiments, both the sleeve 21 and the lamp neck 22 may adopt the samematerial, a material with relatively low thermal conductivity, such asplastic.

As shown in FIG. 22, in this embodiment, both a wall of the sleeve 21and a wall of the lamp neck 22 jointly constitute a wall of the innerchamber of the lamp shell 2. Height of the heat sink 1 in the axialdirection does not exceed height of the sleeve 21 to make the heat sink1 corresponds to the sleeve 21 in a radial direction of the LED lamp.That is, the sleeve 21 has an effect of thermal isolation to preventheat of the heat sink 1 from being conducted to the sleeve 21, so thatelectronic components of the power source 5 world not be affected. Allthe lamp neck 22 is higher than a position of the heat sink 1. That is,in a radial direction of the LED lamp, the heat sink 1 does not overlapthe lamp neck 22. This can make thermal conduction between the heat sink1 and the lamp neck 22, and prevent heat from the heat sink 1 to conductto the inside of the lamp neck 22, so that the electronic componentstherein would not be affected. As a result, in this embodiment, heatconducting efficiency of the wall of the sleeve 21 is configured to belower than heat conducting efficiency of the wall of the lamp neck 22.Advantages of such configuration are as follows: (1) because heatconducting efficiency of the sleeve 21 is relatively low, thermalconduction from the heat sink 1 to the sleeve 21 can be reduced toprevent electronic components in the sleeve 21 form being affected bythe heat sink 1; and (2) because thermal conducting from the heat sink 1to the lamp neck 22 does not need to be considered, heat conductingefficiency of the lamp neck 22 can be increased to be advantageous todissipating heat from the electronic components of the power source 5through the lamp neck 22. This can avoid life shortening of the powersource 5 due to overheating. In this embodiment, in order to make heatconducting efficiency of the wall of the sleeve 21 be lower than heatconducting efficiency of the wall of the lamp neck 22, the sleeve 21 ismade of a material with low thermal conductivity and the lamp neck 22 ismade of a material with relatively high thermal conductivity. Toincrease thermal conductivity of the lamp neck 22, the lamp neck 22 maybe provided with a venting hole 222 or a heat conducting portion (notshown) such as metal or other materials with high thermal conductivity.

As shown in FIG. 22, the lamp neck 22 has an upper portion and a lowerportion. The venting hole 222 is located in the upper portion.Cross-sectional area of the upper portion is less than cross-sectionalarea of the lower portion. Airflow speed in the upper portion is fasterthan that in the lower portion, so that initial speed of air ejectedfrom the venting hole 222 can be increased to prevent hot air fromgathering around the venting hole 222. In this embodiment,cross-sectional area of the lamp neck 22 upward tapers off in the axialdirection to avoid obstruction to air flowing. In this embodiment,cross-sectional area of an inlet of the lower portion of the sleeve 21is greater than that of the upper portion of the lamp neck 22.

As shown in FIG. 1, the venting hole 222 of the lamp neck 22 is of astrip shape and extends along the axial direction of the LED lamp.Because of gravity of the LED lamp itself, the lamp neck 22 would sufferan axial pulling force. The venting hole 222 is configured to be of astrip shape extending the axial direction of the LED lamp, so stressconcentration caused by the venting hole 222 in the lamp neck 22 can beprevented. A maximum diameter of an inscribed circle of the venting hole222 is less than 2 mm, preferably, between 1 mm and 1.9 mm. As a result,the venting hole 222 can prevent bugs from entering and prevent mostdust from passing. On the other hand, the vent 41 can keep betterefficiency of air flowing. On the other hand, if the venting hole 222 isconfigured to annular extending along an circumferential portion of thelamp neck 22, then the lamp neck 22 may be deformed by weight of theheat sink 1 to make the venting hole 222 become larger. This would causethat a maximum diameter of an inscribed circle of the venting hole 222is greater than 2 mm, this cannot satisfy the requirement.

As shown in FIG. 14, the venting hole 222 is outside an outer surface ofthe metal portion 231 in radial directions. This can reduce influence tothe metal portion 231 because of rising air ejected from the ventinghole 222 and prevent heat from being conducted back to the lamp shell 2.

FIG. 36 is a cross-sectional view of the LED lamp of another embodiment.FIG. 37 is a schematic view of arrangement of the convection channels inthe LED lamp. As shown in FIGS. 36 and 37, in some embodiments, afundamental structure of the LED lamp is identical to the LED lamp shownin FIG. 1. In some embodiments, the sleeve 21 has an upper portion and alower portion. The upper portion is connected to the lower portionthrough an air guiding surface 216. A diameter of cross-section of theair guiding surface 216 downward tapers off along the axis of the LEDlamp (along the convection direction of the first heat dissipatingchannel 7 a). That is, the air guiding surface 216 can guide air in thesecond heat dissipating channel 7 b toward the radial outside of theheat sink 1 so as to make air be in contact with more area of the fins11 to bring out more heat of the fins 11. The sleeve 21 includes a firstportion and a second portion in the axial direction. The second portionis a part of the sleeve 21 below the air guiding surface 216 (includingthe air guiding surface 216). The first portion is the other part of thesleeve 21 above the air guiding surface 216 (but not including the airguiding surface 216). Electronic components of the power source 5, whichare located in the second portion of the sleeve 21, include heatintolerance elements such as capacitors, especially electrolyticcapacitors so as to make the heat intolerance elements work in lowtemperature environment (near the first air inlet 2201). In otherembodiments, high heat-generating elements may be disposed in the secondportion of the sleeve 21, such as resistors, inductors and transformers.As for the second heat dissipating channel 7 b, when convection airflows into the second heat dissipating channel 7 b and reaches the lowerportion of the sleeve 21, the convection air would lean against theouter wall of the sleeve 21 to rise. This can generate an effect ofthermal isolation, i.e. heat of the fins 11 is prevented from beingconducted to the inside of the sleeve 21 so that the heat intoleranceelements therein would not be affected. When the convection aircontinues to rise, the convection air will flow outward along radialdirections of the fins 11 under the guide of the air guiding surface 216so as to make the convection air be in contact with more area of thefins 11 to enhance an effect of heat dissipation of the fins 11. In thisembodiment, the inner chamber of the sleeve 21 is of awide-upper-side-and-narrow-lower-side channel structure. Thissignificantly enhances the chimney effect and promotes air flowing inthe sleeve 21. In addition, the venting hole 222 can be designed on thelamp neck 22 away from the vent to further improve the chimney effect.

Next, please refer to FIG. 1, which shows an outline of the LED lamp ofone embodiment. Create a Cartesian coordinate system with the axis ofthe LED lamp as the y-axis, a radial of the LED lamp as the x-axis andthe center of the LED lamp as the origin. A lateral outline of the LEDlamp detours around the axis of the LED lamp 360 degrees to turn aroundto form an contour of the LED lamp (not including the lamp head 23). Anypoint on the outline (usually, the lamp head 23 is a standard one, thus,here does not include the lamp head 23; in detail, the outline iscomposed of the heat sink 1 and the lamp head 22) meets a formula asfollows:y=−ax ³ +bx ² −cx+K

Where K is a constant, range of K is 360˜450, range of a is 0.001˜0.01,range of b is 0.05˜0.3, range of c is 5˜20, preferably, 10˜18, morepreferably, 12˜16.

Hereinafter, as an example, values of a, b and c are supposed asfollows:y=−0.0012x ³+0.2235x ²−14.608x+K

Where range of K is 360˜450.

The above formula can be interpreted as any point on the outline fallingwithin a range between two lines of y=−0.0012x³+0.2235x²−14.608x+360 andy=−0.0012x³+0.2235x2−14.608x+450.

In sum, comprehensively considering various factors of an effect of heatdissipation, principles of thermodynamics and fluid mechanics,satisfying this formula can obtain a great effect of heat dissipation.

In detail, in one aspect, when any point on the outline satisfy theabove formula, a better match between the LED lamp and a lampshade(especially a conic lampshade) as shown in FIG. 39 can be made. Inanother aspect, when any point on the outline satisfy the above formula,the LED lamp axially tapers off from its bottom to top to make overallwidth of the LED lamp approximately progressively decreases. For theheat sink 1, heat from the LED chips 311 can be rapidly conducted to thelower portion of the heat sink 1 to perform heat dissipation. The upperportion of the heat sink 1 mainly relies upon both radiation andconvection to perform heat dissipation. Thus, the lower portion of theheat sink 1 is configured to have more area to perform thermalconduction (the lower portion of the heat sink 1 has large width andheat dissipating area). For the lamp neck 22, the lamp neck 22 has alarge lower portion and a small upper portion. That is, Cross-sectionalarea of the lamp neck 22 axially upward tapers off. When the lamp neck22 dissipate heat from the power source 5 through convection and theventing hole 222 is located in the upper portion of the lamp neck 22,the rising convection airflow would speed up because of taperedcross-sectional area of the lamp neck 22. This makes the convection airejected from the venting hole 222 has faster initial speed, so ejectedair would rapidly leave away from the venting hole 222 to prevent hotair from gathering near the venting hole 222.

In this embodiment, the outline is a smooth or approximately smoothcurve to avoid forming angles with possibility of cutting hands. On theother hand, this makes convection air flowing along the outside of theLED lamp smoother. In this embodiment, the outline of the LED lamp is asubstantially S-shaped curve including a curve on the lamp neck 22 and acurve on the heat sink 1. It is noted that a junction of the lamp neck22 and the heat sink 1 may form an angle which destroys smoothness ofthe curve. However, in general, overall outline still presents smooth.In addition, LED lamps with the same width, whose outlines are curves,in comparison with a straight line, have more area of an outline surfaceto provide more area for thermal radiation.

As shown in FIG. 38, which shows an outline of the LED lamp of oneembodiment. Create a Cartesian coordinate system with the axis of theLED lamp as the y-axis, a radial of the LED lamp as the x-axis and thecenter of the LED lamp as the origin. A lateral outline of the LED lampdetours around the axis of the LED lamp 360 degrees to turn around toform a contour of the LED lamp (not including the lamp head 23). Theoutline includes an outline of the lamp neck 22 and an outline of theheat sink 1.

The lamp neck 22 is used for receiving the power source 5 and primarilyadopts convection to implement heat dissipation to the power source 5.The outline of the lamp neck 22 has a slope a which is a constant. Asshown in FIG. 38, when the outline of the lamp neck 22 is a curve, astraight line may represent an approximate slope of the outline of thelamp neck 22. For example, a line L1 between the top point and thebottom point of the outline of the lamp neck 22 can be used to representan outline of the lamp neck 22 or a line L2 between the center of thetop and the bottom point of the outline of the lamp neck 22 can be usedto represent an outline of the lamp neck 22. In this embodiment, Line L1between the top point and the bottom point of the outline of the lampneck 22 is used to represent an outline of the lamp neck 22 fordescription.

The heat sink 1 primarily adopts conduction to implement heatdissipation to the LED chips 311. The outline of the heat sink 1 has aslope b which is a constant. As shown in FIG. 38, when the outline ofthe heat sink 1 is a curve, a straight line may represent an approximateslope of the outline of the heat sink 1. For example, a line L3 betweenthe top point and the bottom point of the outline of the heat sink 1 canbe used to represent an outline of the heat sink 1 or a line L4 betweenthe center of the top and the bottom point of the outline of the heatsink 1 can be used to represent an outline of the heat sink 1. In thisembodiment, Line L3 between the top point and the bottom point of theoutline of the heat sink 1 is used to represent an outline of the heatsink 1 for description.

In this embodiment, slope a is greater than slope b or an absolute valueof slope a is greater than an absolute value of slope b. Thus, ingeneral, the outline of the lamp neck 22 is steeper than that of theheat sink 1. For the lamp neck 22, under a condition of the same spacerequired for installing the power source 5, in order to guarantee thechimney effect of convection in the lamp neck 22, a certain height ofthe lamp neck 22 must be kept. If a slope of the outline of the lampneck 22 is gentle (small slope), to keep the same height, internalvolume of the lamp neck 22 would increase. However, it is actuallyunhelpful to an installing space of the power source 5. For the heatsink 1, an overall height of the lamp is controlled to guarantee aneffect of heat dissipation. Thus, the heat sink 1 needs to be configuredto be gentle (small slope) to control its overall height. In addition,when the heat sink 1 is gentle (small slope), under a condition of thesame area of heat dissipation, the lower portion of the heat sink 1would have more area for thermal conduction to the LED chips 311.

In this embodiment, slope a is greater than 2, preferably, 2.5˜5, morepreferably, 3˜4, the most preferably, 3.2˜3.8, to make the chimneyeffect of convection in the lamp neck 22 better.

In this embodiment, slope b is smaller than 3, preferably, 1˜2.5, morepreferably, 1.4˜2, the most preferably, 1.5˜1.9, to make the lowerportion of the heat sink 1 have more area for conduction.

In this embodiment, the outline of the LED lamp is a continuous line,i.e. the bottom of the outline of the lamp neck 22 is connected to thetop of the outline of the heat sink 1.

In this embodiment, the outline of the lamp neck 22 is a concave curve.In one example, if a straight line is connected between the top and thebottom of the outline of the lamp neck 22, then all of the outline ofthe lamp neck 22 is inside the straight line (i.e. the side near theaxis of the LED lamp). The outline of the heat sink 1 is a convex curve.In one example, if a straight line is connected between the top and thebottom of the outline of the heat sink 1, then all of the outline of theheat sink 1 is outside the straight line (i.e. the side away from theaxis of the LED lamp). The outline is a smooth or approximately smoothcurve to avoid forming angles with possibility of cutting hands. On theother hand, this makes convection air flowing along the outside of theLED lamp smoother. In this embodiment, the outline of the LED lamp is asubstantially S-shaped or an inverted S-shaped including a curve on thelamp neck 22 and a curve on the heat sink 1. Both a curve on the lampneck 22 and a curve on the heat sink 1 jointly constitute an S-shaped oran inverted S-shaped curve. It is noted that a junction of the lamp neck22 and the heat sink 1 may form an angle which destroys smoothness ofthe curve. However, in general, overall outline still presents smooth.In addition, the lamp neck 22 may be separate from the heat sink 1 (forexample, a certain gap is kept between the lamp neck 22 and the heatsink 1). That is, a curve on the lamp neck 22 and a curve on the heatsink 1 are discontinuous. However, in general, overall outline stillpresents smooth. The outline of the lamp neck 22 is a concave curve, soin the downward section, an enlarging extent of the lamp neck 22increases in size to make the final bottom of the lamp neck 22 have alarger size to connect with the heat sink 1. In one example, an initialposition of the upper portion of the heat sink 1 may obtain a largersize. The outline of the heat sink 1 is a convex curve, so in the upwardsection, a reducing extent of the heat sink 1 increases in size to makethe size reduction of the lower portion of the heat sink 1 becomegentler and gentler. Thus, the lower portion has larger area of the heatsink 1 for heat dissipation. In other embodiments, the outline of thelamp neck 22 may be a straight line and the outline of the heat sink 1is a curve. In addition, the straight line may be parallel to the LEDlamp. In other embodiments, both the outline of the lamp neck 22 and theoutline of the heat sink 1 are straight lines or multiple sectionallines.

In this embodiment, any point on the outline of the lamp neck 22 mustmeet a formula as follows:y=−ax+k1+h,

Where k1 is a constant and h is height of the heat sink 1.

any point on the outline of the heat sink 1 must meet a formula asfollows:y=−bx+k2,

Where k2 is a constant.

In this embodiment, when overall width of the LED lamp is configured tobe between 100 mm and 220 mm, k1 is 100˜200 and k2 is 100˜200. Forexample, when maximum overall width of the LED lamp is 200 mm, k1 is140˜150 and k2 is 170˜200.

In this embodiment, height of the lamp neck 22 is greater than 80% ofheight of the heat sink 1. Because the lamp neck 22 is axially separatefrom the heat sink 1 without overlapping, the power source 5 in the lampneck 22 is less affected by the heat sink 1. Thus, when height of thelamp neck 22 is greater than 80% of height of the heat sink 1, morespace for installing the power source 5 can be obtained and the powersource 5 is less affected by the heat sink 1. In addition, when heat ofthe power source 5 in the lamp shell 2 is dissipated by convection,configuration of height of the lamp neck 22 can guarantee height of thelamp shell 2 to guarantee the chimney effect of convection of heatdissipation.

As shown in FIG. 40, which shows the outline of the LED lamp. Create aCartesian coordinate system with the axis of the LED lamp as the y-axis,a radial of the LED lamp as the x-axis and the center of the LED lamp asthe origin. A lateral outline of the LED lamp detours around the axis ofthe LED lamp 360 degrees to turn around to form a contour of the LEDlamp (not including the lamp head 23). The outline includes an outlineof the lamp neck 22 and an outline of the heat sink 1. As shown in FIG.40, in this embodiment, the outline of the LED lamp includes a firstcurved surface and a second curved surface. Both the first curvedsurface and the second curved surface jointly constitute a curvedsurface of the outline of the LED lamp. The first curved surfaceincludes the curved surface of the outline of the lamp neck 22 or thecurved surface of both the outline of the lamp neck 22 and the outlineof part of the heat sink 1. The second curved surface includes thecurved surface of the outline of the heat sink 1 or the curved surfaceof the outline of part of the heat sink 1.

In this embodiment, the outline of the lamp neck 22 is a smooth orapproximately smooth curve and the outline of the heat sink 1 is asmooth or approximately smooth curve to avoid forming angles withpossibility of cutting hands. On the other hand, this makes convectionair flowing along the outside of the LED lamp smoother. In thisembodiment, the radius of curvature of the outline of the lamp neck 22is greater than the radius of curvature of the outline of the heat sink1. It is noted that the phrase “the radius of curvature of the outlineof the lamp neck 22 is greater than the radius of curvature of theoutline of the heat sink 1” means that the radius of curvature of 60% ofthe outline of the lamp neck 22 being greater than the radius ofcurvature of 60% of the outline of the heat sink 1 can be deemed as theradius of curvature of the outline of the lamp neck 22 being greaterthan the radius of curvature of the outline of the heat sink 1.

As shown in FIG. 40, in this embodiment, a radius of curvature of theoutline of the lamp neck 22 is 120 mm˜3000 mm, preferably, 150 mm˜200mm, more preferably, 160 mm˜190 mm, and the most preferably, 170 mm˜185mm. A radius of curvature of the outline of the heat sink 1 is 30 mm˜150mm, preferably, 70 mm˜130 mm, more preferably, 80 mm˜120 mm, and themost preferably, 90 mm˜110 mm. Based on the abovementioned, if at least60% of the radius of curvature falls in the range or curvature of acurve which is the most consistent with the outline can be deemed as theradius of curvature of the outline of the lamp neck 22 and the heat sink1. For example, if a radius of curvature of at least 60% of the outlineof the lamp neck 22 is 180 mm, then the radius of curvature of the lampneck 22 can deemed as 180 mm. Based on the abovementioned, it can alsobe interpreted that a curve similar to an outline can representcurvature of the outline. That is, an outline itself may not be a curve.In some embodiments, considering overall width of the LED lamp, theoutline of the lamp neck 22 and the outline of the heat sink 1 areseparately related to overall width of the LED lamp. If width of the LEDlamp (a size of the widest portion of the LED lamp) is L, then theradius of curvature of the outline of the lamp neck 22 is 0.6 L˜15 L,preferably, 0.75 L˜L, more preferably, 0.8 L˜0.95 L, and the mostpreferably, 0.85 L˜0.925 L; and the radius of curvature of the outlineof the heat sink 1 is 0.15 L˜0.75 L, preferably, 0.35 L˜0.65 L, morepreferably, 0.4 L˜0.6 L, and the most preferably, 0.45 L˜0.55 L. Thatis, both curvature of the outline of the lamp neck 22 and curvature ofthe outline of the heat sink 1 vary with change of overall width of theLED lamp. In some embodiments, if an outer diameter of the largestportion of the lamp neck 22 is R, then curvature of the outline of theheat sink 1 must be greater than L/2-R/2 to guarantee both the heat sink1 having sufficient height and the chimney effect of the second heatdissipating channel 7 b.

In this embodiment, a center angle c occupied by the outline of the lampneck 22 is 10˜50 degrees, preferably, 20˜35 degrees, and morepreferably, 25˜30 degrees, to guarantee both the lamp neck 22 havingsufficient height and the chimney effect of convection in the lamp neck22.

In this embodiment, a center angle d occupied by the outline of the heatsink 1 is 40˜120 degrees, preferably, 55˜90 degrees, more preferably,65˜80 degrees, and the most preferably, 70˜75 degrees, to controloverall height of the heat sink 1.

The above depiction has been described with reference to theaccompanying drawings, in which exemplary embodiments of the disclosureare shown. This disclosure may, however, be embodied in many differentforms and should not be construed as limited to the embodiments setforth herein. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art.

What is claimed is:
 1. An LED (light emitting diode) lamp comprising: alamp shell including a lamp head, a lamp neck and a sleeve, the lamphead connects to the lamp neck which connects to the sleeve; a passiveheat dissipating element having a heat sink connected to the lamp shell,wherein the heat sink comprises fins and a base, the sleeve of the lampshell is located in the heat sink, the lamp neck projects from the heatsink, height of the lamp neck is at least 80% of height of the heatsink; a power source having a first portion and a second portion,wherein the first portion of the power source is disposed in both thelamp neck and the lamp head of the lamp shell, and the second portion ofthe power source is disposed in the heat sink of the passive heatdissipating element; a light emitting surface connected to the heat sinkof the passive heat dissipating element and comprising LED chipselectrically connected to the power source, wherein the light emittingsurface and the heat sink are connected to form a heat transferring pathfrom the LED chips to the passive heat dissipating element; a first heatdissipating channel formed in a first chamber of the lamp shell fordissipating heat generated from the power source while the LED lamp isworking, and the first chamber is located between bottom of the LED lampand an upper portion of the lamp neck; and a second heat dissipatingchannel formed in the heat sink and between the fins and the base of theheat sink for dissipating the heat generated from the LED chips andtransferred to the heat sink; wherein the first heat dissipating channelcomprises a first end on the light emitting surface to allow air flowingfrom outside of the LED lamp into the first chamber, and a second end onthe upper portion of the lamp neck of the lamp shell to allow airflowing from inside of the first chamber out to the LED lamp; whereinthe second heat dissipating channel comprises a third end on the lightemitting surface to allow air flowing from outside of the LED lamp intothe second heat dissipating channel, and flowing out from spaces betweenevery adjacent two of the fins; wherein a third aperture is located in acentral region of the light emitting surface, and the third apertureforms an air intake of both the first heat dissipating channel and thesecond heat dissipating channel; wherein a lateral outline of the LEDlamp detours around an axis of the LED lamp 360 degrees to turn aroundto form an contour of the LED lamp, any point on the outline meets aformula as follows:y=−ax ³ +bx ² −cx+K; where K is a constant, and range of the constant ofK is 360˜450; range of value of a is 0.001˜0.01, range of value of b is0.05˜0.3, and range of value of c is 5˜20; wherein overall weight of theLED lamp is less than 1.7 kg, when the LED lamp is provided with powerof 200 W, the LED chips are lit up and emit luminous flux of at least25000 lumens.
 2. The LED lamp of claim 1, wherein the values of a, b andc are to meet a relation of follows:y=−0.0012x ³+0.2235x ²−14.608x+K.
 3. The LED lamp of claim 2, whereinthe heat sink includes a lower portion and an upper portion, the lowerportion of the heat sink has large width and heat dissipating area thanthe upper portion.
 4. The LED lamp of claim 3, wherein cross-sectionalarea of the lamp neck axially upward tapers off.
 5. The LED lamp ofclaim 4, wherein the outline of the LED lamp is a substantially S-shapedcurve including a curve on the lamp neck and a curve on the heat sink.6. The LED lamp of claim 5 further comprising a lamp cover with a lightoutput surface and an end surface, wherein the end surface is formedwith a vent to let air flowing from outside of the LED lamp into boththe first channel and the second channel through the vent.
 7. The LEDlamp of claim 6, wherein the first end is projected onto the end surfacein the axis of the LED lamp to occupy an area on the end surface, whichis defined as a first portion, another area on the end surface isdefined as a second portion, and the vent in the first portion isgreater than the vent in the second portion in area.
 8. The LED lamp ofclaim 7, wherein the heat sink comprises first fins and second fins,bottoms of both the first fins and the second fins in the axis of theLED lamp connect to the base, the first fins interlace with the secondfins at regular intervals, and one of the second fins includes a thirdportion and two fourth portions, the two fourth portions are symmetricalabout the third portion.
 9. The LED lamp of claim 8, wherein each of thefirst fins is divided into two portions in a radial direction of the LEDlamp, the two portions are divided with a gap portion, the third portionis connected to the fourth portion through a transition portion, thetransition portion has a buffer section and a guide section, a directionof any tangent of the guide section is separate from the gap portion.10. The LED lamp of claim 9, wherein the second end on the upper portionof the lamp neck of the lamp shell is formed with a venting hole, thelamp shell has an airflow limiting surface which extends radiallyoutwardly and is located away from the venting hole, the airflowlimiting surface cloaks at least part of the fins.
 11. The LED lamp ofclaim 10, wherein upper portions of at least part of the fins in theaxial direction of the LED lamp correspond to the airflow limitingsurface.
 12. The LED lamp of claim 11, wherein the sleeve has an upperportion and a lower portion, the upper portion is connected to the lowerportion through an air guiding surface, a diameter of cross-section ofthe air guiding surface downward tapers off along the axis of the LEDlamp.
 13. The LED lamp of claim 12, wherein the sleeve includes a firstportion and a second portion in the axial direction, the second portionis a part of the sleeve below the air guiding surface, electroniccomponents of the power source, which are located in the second portionof the sleeve, include electrolytic capacitors.
 14. The LED lamp ofclaim 13, wherein the power source includes a heat-generating element,the heat-generating element is in contact with the lamp head through athermal conductor and the heat-generating element is fastened to thelamp head through the thermal conductor.
 15. The LED lamp of claim 14,wherein the lamp head includes a metal portion, at least part of aninner side of the metal portion constitutes a wall of the inner chamberof the lamp shell to make the thermal conductor directly connecting withthe metal portion and performing heat dissipation by the metal portion.